question: Background: The impact of the Coronavirus Disease 2019 (COVID-19) pandemic on people's mental health has been gradually revealed. Emotional responses under this pandemic have been a focus. This study aimed to observe the time map and predictors of transient daily emotions (on-spot emotional responses) during the COVID-19 outbreak in Chinese people. Methods: A total of 133,027 Chinese people from all cities and areas of China took part in this 25-day online investigation from January 27 to February 20, 2020. Hierarchical regression was carried out. Results: Chinese people reported mild positive and negative emotions during COVID-19, and the trend was that negative emotions declined and happy emotion increased in a curvilinear style. Females reported stronger on-spot negative emotions. Young and unmarried people, and individuals with lower risk perception reported lower negative emotions and higher happiness, while people with postgraduate or higher education, medical staff and patients, and individuals coming from areas with more confirmed cases, experienced stronger positive and negative emotions. In the regression model, risk predictors of negative emotions were being female, being older in age, having postgraduate or higher education, living in a city with more confirmed cases, being a patient or medical staff, and having higher risk perception, while protective predictors of negative emotions were being unmarried, having high-school or college education, and later investigating date. Notably, been married was negative predictor of happiness. Conclusions: This large sample, 25-day successive online investigation is among the first to reveal the time map of on-spot emotions in Chinese people under the COVID-19 pandemic. The risk and protective predictors of on-spot negative emotions help to recognize vulnerable people under pandemic conditions and further develop more targeted early interventions for future crises. © 2021 The Authors