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According to the characteristics of large underground cavs,by using the safety factor of surrounding rock mass point as the control standard of cav stability,RandWPSO-LSSVM optimization feedback method and flow process of large underground cav anchor parameters were established.By applying the optimization feedback method to actual project,the best anchor parameters of large surge shaft five-tunnel area underground cavem of the Nuozhadu hydropower station were obtained through optimization.The results show that the predicted effect of LSSVM prediction model obtained through RandWPSO optimization is good,reasonable and reliable.Combination of the best anchor parameters obtained is 114131312,that is,the locked anchor bar spacing is 1 m × 1 m,pre-stress is 100 kN,elevation 580.45-586.50 m section anchor bar diameter is 36.00 mm,length is 4.50 m,spacing is 1.5 m × 2.5 m; anchor bar diameter at the five-tunnel area side wall is 25.00 mm,length is 7.50 m,spacing is 1 m x 1.5 m,and the shotcrete thickness is 0.15 m.The feedback analyses show that the optimization feedback method of large underground cav anchor parameters is reasonable and reliable,which has important guiding significance for ensuring the stability of large underground cavs and for saving project investment.