The fitting formulas of variable physical parameters of four new P-type thermoelectric materials (Bi0.5Sb1.5)Te3 prepared by Ingot method, BM method, S-MS method and Te-MS method were obtained by point method. The influence of temperature on thermoelectric materials prepared by different methods was analyzed. The relation curve between dimensionless merit figure and absolute temperature of thermoelectric materials is obtained. In addition, the influence of different preparation processes on the maximum coefficient of performance (COP) of thermoelectric cooler composed of thermoelectric materials was studied from the thermodynamic aspect. The results show that: Compared with the other three preparation methods, the new P-type thermoelectric material (Bi0.5Sb1.5)Te3 prepared by Te-MS method has the largest coefficient of merit and the best thermoelectric performance. The thermoelectric refrigerator with the new P-type thermoelectric material (Bi0.5Sb1.5)Te3 prepared by Te-MS method has the maximum COP, which can reach 2.49, which is 34.59 %, 37.57 % and 25.76 % higher than those prepared by the other three methods, respectively.