Introduction Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic serious complication of controlled ovarian stimulation during assisted reproductive technology, the aim of our research is to explore the differences of pregnancy outcome between severe OHSS patients and the non-OHSS IVF patients, and also compare the pregnancy ourtome of different ascites drainage way. Design This is a retrospective cohort analysis carried out in a University-affiliated reproductive center from 2012 to 2019, between 359 women with severe OHSS following ascites draining and 345 non-OHSS women (matched by age and retrieved oocyte number).We examined the rates of clinical pregnancy, multiple pregnancies, miscarriage, live birth and preterm delivery between the two groups. Within the OHSS group (central venous catheter group vs paracentesis group), odds ratios (ORs) and 95% confidence intervals (CIs) of measure of clinical pregnancy were also analyzed. Result The biochemical pregnancy loss rate of non-OHSS patients was significantly higher than that of severe OHSS patients (11.1% vs 0.6%), the live birth, multiple pregnancy (twin pregnancy) was much more in severe OHSS group than in control group(88.9% vs 73.5%; 57.6% vs 28.1% respectively), and there was no significant difference between singleton and twin preterm rate and neonatal birth weight between OHSS and control group. Binary logistic regression analysis revealed multiple pregnancy and long-protocol showed relatively high odds ratio, suggest that the long-protocol of COS and multiple pregnancy are the risk factor of severe OHSS. Among severe OHSS following ascites draining, in comparison with abdominal paracentesis and central venous catheter, the ascites volume in central venous catheter group was much more than abdominal paracentesis group, there was significant difference between the two groups. There was no significant difference between the two groups in comparison of live birth, and the birth weight of singleton and twin between these two groups. but the premature birth rate of singleton in group 1 was 9.3% (10/107), whereas in group 2, it was 3.75%. Conclusion In conclusion, this preliminary report suggests that for the IVF-ET patients, less basic follicle number, GnRH antagonist cycle, singleton maybe the protective factors for the late-onset OHSS. Paracentesis and central venous catheter are all the effective modality to manage the ascites for the severe OHSS patients. For the patients who have the possibility of repeated paracentesis, catheter is a safe and effective way.