The detection of the jet temperature field in an aircraft engine tail is an effective way to reflect the running state of an engine. To solve the complicated detection process of current laser diagnostic methods, the colored background oriented Schlieren (CBOS) method was proposed to obtain a tail jet temperature field. First, the background Schlieren image with three-color points was collected for the exhaust gas temperature (EGT) field of the engine. Then the refractive index field of the engine exhaust was obtained according to the proposed CBOS method. Finally, the three-dimensional EGT field was reconstructed through the refractive index field. The simulation and the experimental results show the feasibility and effectiveness of the proposed method.