keeping cooking for 200 minutes and obtaining the straw pulp after pressing and washing wherein in the cooking liquor ammonium sulfite is used in an amount of 10 of the bone dry raw material by weight sodium hydroxide is used in an amount of 5 of the bone dry raw material by weight and liquor ratio is 1 8 the straw pulp has a hardness with potassium permanganate value of 16 a tensile index of 38 nm g a tear index of 4 8 mn u00b7 m 2 g a folding number of 4 6 kpa u00b7 m 2 g a whiteness of 35 the pulp is used to make the food wrap paper base paper with dirt count of 120 u00b7 m 2 per 0 3 2 0 mm 2 bursting strength of 75 kpa and whiteness of 28 60 the dirt count of the invention is measured by the testing method of national standard gb t 1541 1989 paper and board determination of dirt the straw pulp fiber of the invention is defined as the straw pulp fiber which is obtained by the method of the prior art such as cooking and washing or cooking washing and oxygen delignification the cooking of the invention comprises but not limited to ammonium sulfite and alkaline method the alkaline method comprises anthraquinone sodium hydroxide sulfate.