Background Suicide has become a major public health issue of global concern. Suicidal ideation represents the initial psychological and one of the strongest predictorsactivities associated with suicidal behavior. Suicidal ideation is a dynamic state factor rather than a static trait factor, so it is necessary to study the development trajectory of suicidal ideation and its related factors.Objective To investigate the development trajectory and relatedfactors of suicide ideation college students.

From 2019 to 2021,1438 college students in a university in Guangdong Province were selected for three longitudinal tracking each October by using the method of convenient sampling. The Self-rating ideas of suicide scale (SIOSS) was used to measure the level of suicide ideation. Data analysis was mainly based on the Latent Growth Mixed Model(LGMM) to analyze the development trajectory of students’ suicide ideation. Multivariate Logistic Regression model was established to analyze the related factors to the variation of each potential category of suicidal ideation.

From 2019 to 2021, the total scores of college students’ suicidal ideation were 3.79±2.87, 3.71±2.90 and 3.32±2.87, showing a decreasing trend over time. The development tendencies of college students’suicide ideation have been classified into 3 categories: C1 group(worsening suicidal ideation group)(11.8%)，C2 group(persistent low suicidal ideation group)(79.6%), and C3 group (relieving suicidal ideation group) (8.6%). Compared with C1 group, college students who had an average (OR=2.52, 95% CI:1.31-4.86) or happy childhood (OR=3.95,95% CI:2.02-7.74), no history of suicide attempt (OR=9.03，95% CI:3.49-23.36), and were extroverted (OR=1.03, 95% CI:1.01-1.05) were more likely to enter C2 group. Students who were from cities (OR=0.54, 95% CI:0.31-0.93),got high neuroticism scores (OR=0.86, 95% CI:0.84-0.88) were less likely to enter the C2 group. College students with happy childhood life(OR=3.29, 95% CI:1.40-7.74)were more likely to enter the C3 group, but students from cities(OR=0.37, 95% CI:0.18-0.78)were less likely to enter the C3 group.

The development tendencies of college students’ suicide ideation can be classified into three categories: worsening suicidal ideation group,persistent low suicidal ideation group, and relieving suicidal ideation group. The developmental trajectory of suicidal ideation is related to birthplace, childhood life, suicide history, and personality traits.