Accessing good quality abortion care is a fundamental human right and contributes to achieving Sustainable Development Goals. However, well-designed abortion care that meets women's needs is limited. This study aims to systematically develop an intervention to promote the psychological well-being of Chinese women undergoing an abortion. A five-step iterative approach informed by intervention mapping was undertaken to determine the intervention design. Step 1 used in-depth interviews with 14 Chinese women undergoing an abortion to assess real-life stressors and support needs. We identified eight stressors and found women's support needs varied with the time trajectory of the abortion. Step 2 used a focus group discussion with care providers to select modifiable stressors that impact negative psychological outcomes. In Step 3 and Step 4, we determined and integrated the exact strategies to eliminate or mitigate possible modifiable stressors by incorporating information from in-depth interviews and the Transactional Model of Stress and Coping. The integrated strategies were instructional support, informational support, and timely communication. In Step 5, we composed the detailed intervention design according to the best available evidence and, to confirm content validity, consulted 10 women who had undergone abortion in the previous 2-6 weeks. The intervention was titled STress-And-coping suppoRT (START), which included four interacting components: (1) a face-to-face consultation at the first appointment; (2) a printed booklet with information on abortion, self-care, and managing emotions and intimate relationships; (3) a WeChat-based online public profile page offering the same information as the booklet; (4) a telephone hotline. This study paves the way for a new approach to addressing the psychological needs of women experiencing abortion in China. The rigorous process provides an example of developing tailored health promotion interventions.