The purpose of this study was to investigate the suitability of different spent mushroom sawdust wastes (SMSWs) and different proportions of SMSWs as potential substrates for the cultivation of Auricularia polytricha by evaluating yield and biological efficiency of the fruiting body. Nine SMSWs were respectively utilized as the main ingredient in the cultivation of A. polytricha. Then, spent Pleurotus eryngii, Pleurotus cystidiosus, and Pleurotus ostreatus sawdust wastes were screened among these nine SMSWs to be utilized as substrate and to determine the suitable proportion of SMSW in the cultivation of A. polytricha based on their yields and biological efficiencies. The highest yield and biological efficiency (total of two flushes) of A. polytricha cultivation on a single SMSW substrate was obtained with spent P. eryngii sawdust waste, followed by spent P. cystidiosus and P. ostreatus sawdust wastes. These three SMSWs were then applied in nine combination substrates, which were screened based on yield and biological efficiency for cultivation of A. polytricha. The combination substrate with the highest yield and biological efficiency of A. polytricha cultivation was P. eryngii (PES) + P. cystidiosus spent sawdust (PCYS) (235.4 g/bag yield and 58.85% biological efficiency); its yield was 1.62 folds higher than that of the control. From the results, we found that it was feasible to use spent sawdust wastes of P. eryngii and P. cystidiosus to replace sawdust for cultivation of A. polytricha.