Objective: To investigate the prevalence and influencing factors of suicidal ideation and the effects of daily stress and positive mental health on suicidal ideation among college freshmen in Wuhan. This study aims to provide a scientific basis for mental health improvement and suicide prevention among college students from the perspective of positive psychology. Methods: In December 2020, a convenient sampling method was used to select 2 592 freshmen from three universities in Wuhan. Demographic information, suicidal ideation, positive mental health, and daily stress were assessed. T test and Logistic regression analysis were used to analyze the status and influencing factors of suicidal ideation among college freshmen. Results: The one year prevalence of suicidal ideation was 27.5%. Freshmen with suicidal ideation had higher daily stress scores and daily stress scores in different domains than freshmen without suicidal ideation( t =-13.00--4.68)， the positive mental health scores of freshmen with suicidal ideation were lower than freshmen without suicidal ideation ( t =17.14， P <0.01). Female ( OR=1.72, 95%CI =1.44-2.05), the higher education level of the mother (OR=1.27, 95%CI=1.05-1.53) and total experience of daily stress ( OR=1.11, 95%CI =1.09- 1.13 ) were associated with risk of oneyear suicidal ideation. Positive mental health was negatively associated with suicidal ideation ( OR=0.88, 95%CI=0.87-0.90, P <0.01) and had a moderating effect on the association between daily stress and suicidal ideation. Conclusion Suicidal ideation among college freshmen is closely related to daily stress and positive mental health. It is necessary to pay close attention to daily stress of freshmen and reduce suicidal ideation by improving positive mental health.