To explore the longitudinal-causal relationship between college students' overall family functioning and their Internet altruistic behaviors, so as to provide ideas for developing mental health education in universities.

By using a convenience sampling method, the Overall Family Functioning Rating Scale and the Internet Altruistic Behaviors Scale were adopted to conduct a two-stage follow'up survey (T1:November 2023, T2:October 2024) among 705 students from seven universities in Jiangsu Province over a period of one year. Repeated measures ANOVA, Pearson correlation analysis, and cross-lagged analysis were used for statistical analysis.

The overall family functioning of college students was relatively stable over time (T1:2.99±0.83; T2:3.01±0.57) [F_{(1, 703)}=0.68, P>0.01]; however, the main effect of gender was statistically significant [boys: T1(2.98±0.78), T2(2.99±0.67);girls: T1(3.01±0.91), T2(3.01±0.42);F_{(1, 703)}=6.91, P < 0.01], with female college students having a higher overall family functioning level than male college students. The Internet altruistic behaviors of college students showed certain dynamic changes (T1:2.86±0.39; T2:3.05±0.46) [F_{(1, 703)}=10.19, P < 0.01], and the post-test Internet altruistic behaviors levels of both male and female college students were higher than those of the pre-test; network altruistic behavior was not statistically significant on the sex main effect [bodys: T1(2.87±0.44), T2(3.05±0.31);girls: T1(2.85±0.36), T2(3.06±0.65);F_{(1, 703)}=2.50, P>; 0.05]; the interaction between time and gender for Internet altruistic behaviors were statistically significant [F_{(1, 703)}=6.64, P < 0.01]; the concurrent and lagged correlations between the overall family functioning and Internet altruistic behaviors of college students were all positive (r=0.35-0.57, P < 0.01); the pre-test overall family functioning could positively predict the post-test Internet altruistic behaviors (β=0.15, P < 0.01).

The overall family functioning of college students is relatively stable, while their Internet altruistic behaviors show certain development and changes. The overall family functioning of college students can directly predict their Internet altruistic behaviors, and there is a certain degree of causal relationship between the two.