Background: Abortion is a stressful life event associated with wide variability in women's perceptions and adjustment. There is scarce evidence on interventions to help women cope with abortion and achieve positive psychological health outcomes. This study tested the effect of a stress and coping theory-formed intervention (START) on depression and coping of Chinese women undergoing a first-trimester abortion. Methods: A randomized controlled trial was conducted at a Chinese metropolitan hospital. 110 participants were recruited and randomized to intervention group (START + standard care) or control group (standard care) with a 1:1 allocation ratio. The primary outcome was depression at two-week post-abortion. Surveys were completed by participants when they sought abortion services (baseline), two and six-week post-abortion. Results: At two-week post-abortion, women allocated to the intervention group compared to the control group, had significantly lower depression scores (aOR −2.81 [−4.12 to −1.50]), higher problem-focused coping (aOR 1.64 [0.36–2.93]), lower dysfunctional coping (aOR −2.29 [−3.69 to −0.89]), higher self-efficacy (aOR 3.17 [−0.42–5.94]), and higher personal growth scores (aOR 4.41 [0.30–8.53]). Lower depression scores at two-weeks were mediated by lower dysfunctional coping (mediated effect 0.96 [0.25, 1.74]; proportion of overall effect 36 % [9 %, 65 %]). Conclusion: Chinese women allocated to receive START had lower depression and better coping at two-week post-abortion. This brief, online intervention contributed to women's self-efficacy and positive perceptions of social support, abortion experience, and personal growth. Maintenance of the effects need further research.