Objective · To discusses the high risk factors and therapy strategies for ovarian hyperstimulation syndrome (OHSS). Methods · Seventy-seven cases with moderate and severe OHSS were collected to be retrospectively analyzed in Shanghai Ninth People’s Hospital affiliated to Shanghai Jiao Tong University School of Medicine from January 2010 to December 2016. Results · Compared with non-pregnant patients, pregnant patients were more likely to have severe OHSS (P<0.05). Embryo transfer patients who underwent ovulation induction and oocyte retrieval became severe OHSS much more easily and had a much longer hospital stay than oocyte retrieval patients (P<0.05). Pumping ascites and pleural effusion or not has no effect on the length of hospital stay and the usage of low molecular dextran for patients with severe OHSS. Conclusion · The risk of OHSS should be evaluated to determine whether or not to carry out a fresh embryo transfer in patients who underwent ovulation induction and oocyte retrieval. For OHSS patients who have undergone embryo transfer or pregnancy, more attention should be paid to the progress of the disease, and individualized treatment is required.