Objective：The effect of mifepristone in the treatment of low-risk Cesarean Scar Pregnancy（CSP） was monitored by three-dimensional ultrasound, and its application value was evaluated. Methods：23 CSP patients with systemic score less than 5 and 19 intrauterine pregnancy (IUP) patients with scar at the same time in our hospital were selected. The changes of blood vessel index (VI), blood flow index (FI) and blood vessel flow index (VFI) around the gestational sac were monitored by three-dimensional ultrasound before and after the application of mifepristone in the two groups, and the therapeutic effect was evaluated. Results: There was no significant difference in VI (before) - VI (after), FI (before) - FI (after), VFI (before) - VFI (after) index between the two groups before and after mifepristone treatment (P > 0.05), and There was no difference in efficiency between the two groups. There was no significant difference in the effective rate between the two groups. CONCLUSION: Three-dimensional ultrasound can monitor the efficacy of mifepristone in the treatment of CSP patients with score less than 5. It is considered that routine drug abortion combined with uterine curettage is feasible for these CSP patients.