A series of double perovskite oxide Pr_(2-x)Tb_xCoMnO₆ (x=0, 0.05, 0.1, 0.15) was prepared by high temperature solid state reaction. The effect of Tb-doping on the Curie temperature, magnetic entropy change and magnetic phase transition of double perovskite oxide Pr₂CoMnO₆ was investigated by analyzing the relevant data. The results show that the series of double perovskite oxides Pr_(2-x)Tb_xCoMnO₆ (x=0,0.05,0.1,0.15) all is good single-phase with crystallographic structure of monoclinic P2₁/n; they all have two magnetic transition points (T_C1 and T_C2); T_C1 and T_C2 decrease with the increasing Tb-content; within the desired temperature region, as the temperature decreases the state of the prepared four double perovskite oxides underwent the following transition: paramagnetic state, paramagnetic-ferromagnetic and coexistence state; by a given external magnetic field of 7 T, the maximum magnetic entropy change ΔS_{Mof the prepared four double perovskite oxides is -1.862, -1.779, -1.768 and -1.766 J/(kg·K) respectively. In other word, Tb-doping makes the maximum magnetic entropy change smaller, but increases its half-height wide temperature range. It can be judged that among others, Pr1.9Tb0.1CoMnO6 is the most potential candidate as a high-temperature magnetic refrigeration material especially, regarding to its RCP value; Based on the analysis of the Arrott curve, the recalibration curve and the Loop curve, the four double perovskite oxides underwent a first-order phase transition during the process.}