Objective To investigate the effect of percutaneous balloon mitral valvuloplasty under echocardiographic guidance for patients with moderate to severe mitral stenosis during pregnancy. Methods A retrospective observational study was conducted to include pregnant women who were diagnosed with moderate to severe mitral stenosis and underwent percutaneous balloon mitral valvuloplasty under echocardiographic guidance in Fuwai Hospital from August 2018 to June 2022, and their baseline characteristics, surgical outcomes, echocardiographic results, and follow-up results were analyzed. Results A total of 3 pregnant women aged 30-35 years, with gestational age of 19-26 weeks, and New York Heart Association (NYHA) function class Ⅲ were included. All the procedures were successfully performed. The mitral valve orifice area increased from 0.9 cm2 preoperatively to 2.1 cm2 postoperatively. The mean transvalvular pressure gradient decreased from 15.0 mm Hg preoperatively to 6.7 mm Hg postoperatively. No perioperative adverse events occurred. The follow-up time ranged from 3 to 48 months. All patients delivered uneventfully and returned to normal life, with maternal-fetal safety. Conclusion Percutaneous balloon mitral valvuloplasty under echocardiographic guidance is a feasible and effective procedure for the treatment of patients with moderate to severe mitral stenosis in pregnancy, with satisfactory maternal-fetal outcomes.