Ernst Tremmel was accused of 1,075 counts of accessory to murder for his time working at the death camp in German-occupied Poland.
Tremmel worked at the camp from November 1942 to June 1943.
The trial was to have started on Wednesday in the western city of Hanau, where Auschwitz survivors were expected to give testimony.
"All the appointments related to these proceedings have now been cancelled," the regional court in Hanau said in a brief statement. No cause of death was released.
Tremmel served with an SS Totenkopf unit processing the arrival of prisoners at the camp and was allegedly directly involved in three transports, from Berlin, the French city of Drancy, and Westerbork in the Netherlands.
"Among the deportees, at least 1,075 people were cruelly murdered immediately after their arrival at Auschwitz," the Hanau court said when it announced the trial in February.
Because Tremmel was aged 19 or 20 at the time of his alleged crimes, he was to have been tried under juvenile criminal law despite his advanced age.
Because of his frail health, the court had ordered hearings to be limited to four hours per day.
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Why did ordinary people commit atrocities in the Holocaust?
The legal foundation for prosecuting ex-Nazis changed in 2011 when German authorities convicted former death camp guard John Demjanjuk solely on the basis of his having worked at the Sobibor camp in occupied Poland.
Last July, Oskar Groening, dubbed the "Bookkeeper of Auschwitz", was sentenced to four years in prison for being an accessory to the murders of 300,000 people at the camp.
But the trial of 95-year-old Hubert Zafke, a former Auschwitz medic, was suspended for the second time last month due to his ill health.
A third man, former SS guard Reinhold Hanning, 94, went on trial on 11 February accused of complicity in 170,000 deaths at Auschwitz.
Further investigations are ongoing.

At least 20 shots were fired from an automatic weapon through the living room window of a house in Carrigart Crescent at about 01:45 GMT on Monday.
There was no-one else in the house at the time.
Police are investigating a possible link to a silver Skoda car which was seen in the Carrigart area before the shooting.
It was stolen from Dublin in December and had fake number plates.
The vehicle was found burnt out in the New Line area a short time after the shooting.
Ch Insp Jon Burrows has appealed for the public to come forward with information.
"Someone must know what the background to this was," he said.
"Why was this person targeted? It was a very orchestrated, carefully planned attack.
"Is there anything happening in that area? Do you know anything about that individual who was targeted?
"We need your help in solving this crime."

Ambulance staff informed police of the death of the boy, who was eight months old, at around 10:30 BST on Wednesday.
Officers were called to Brownhills Road in Newton Abbot, and subsequently closed off the road.
A spokesman for Devon and Cornwall Police said a 27-year-old man had been taken into custody in relation to the death.
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Scenes of crime officers and police attended the house to undertake initial investigations, where they found a sibling of the child along with two adults.
Devon and Cornwall Police said they were not looking for anyone else in relation to the case.

They said there had been 63 confirmed cases of the mosquito-borne illness so far this year, up from seven in the whole of 2016.
Most of the cases have been in rural areas of Minas Gerais state, a Ministry of Health statement said.
The government has sent two million doses of yellow fever vaccines to the state.
The governor of Minas Gerais has declared a 180-day state of emergency.
Source: WHO
Of the 63 confirmed cases in Brazil, 35 have proved fatal, Brazilian Health Ministry figures show.
That is the highest number of deaths since at least 2008, the year to which Ministry of Health records date back.
There have also been three confirmed cases in Sao Paulo, Brazil's most populous state, and one each in Espiritu Santo and Bahia, which both neighbour Minas.
It is not clear what has caused the rise in cases.
A 93-year-old former guard at Auschwitz has died a week before he was due to stand trial in Germany.
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A 31-year-old man is in a critical condition in hospital after he was shot in the head in Lurgan in County Armagh.
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Police are investigating the "suspicious" death of a baby boy in Devon.
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Health officials in Brazil say there has been a sharp rise in the cases of yellow fever in the country.