Objective To exploring the effectiveness of perioperative application of new surgical clinical classification and staging for myasthenia gravis (MG) in reducing the incidence of postoperative myasthenic crisis (MC). Methods The clinical data of patients with generalized MG admitted to the Comprehensive Treatment Center for Myasthenia Gravis of Henan Provincial People’s Hospital from January 2018 to June 2022 were retrospectively analyzed, who were scored with myasthenia gravis-activities of daily living (MG-ADL) score and quantification of the myasthenia gravis (QMG) score at the first visit, 1 day before surgery, and 3 days after surgery. The patients were divided into a group A (typeⅡ) and a group B (typeⅢ+Ⅳ+Ⅴ) by the new surgical clinical classification and staging of MG according to the disease progression process, and all patients underwent expanded thoracoscopic thymus (tumor) resection after medication and other interventions to control symptoms in remission or stability. The incidence of MC and the efficiency rate after surgery were analyzed. The normal distribution method and percentile method were used to calculate the unilateral 95% reference range of the QMG score and MG-ADL score. Results Finally 126 patients were enrolled, including 62 males and 64 females, aged 13-71 years, with an average age of 46.00±13.00 years. There were 95 patients in the group A and 31 patients in the group B, and the differences of the preoperative baseline data between the two groups were not statistically significant (P>0.05). The incidence of postoperative MC was 1.05% (1/95) in the group A and 3.23% (1/31) in the group B (P>0.05). The effective one-sided 95% reference range of the QMG score and MG-ADL score 1 day before surgery was 0-7.75 and 0-5.00, and there was no postoperative death in both groups. Conclusion The new surgical clinical classification and staging of MG can guide the timing of surgery, which can benefit patients undergoing surgery for MG and greatly reduce the incidence of postoperative MC.