Engine after-treatment test system

The invention discloses an engine after-treatment test system. The engine after-treatment test system comprises an engine tail gas pipe, a heat exchanger, an after-treatment part, an exhaust pipe anda controller, wherein the controller is used for controlling the communication relation between the engine tail gas pipe and the heat exchanger to form a first flow path; the controller is further used for controlling the communication relation between the engine tail gas pipe and the after-treatment part to form a second flow path; and the controller is also used for controlling the communicationrelation between the engine tail gas pipe and the exhaust pipe to form a third flow path; and the heat exchanger communicates with the after-treatment part, and the after-treatment part communicateswith the exhaust pipe. The original exhaust tail gas of an engine can be directly detected, and meanwhile, an after-treatment system is directly tested, so that the subsequent development design is facilitated. When the engine