The utility model discloses a load simulation and test system of an engineering machine, which comprises a motive power source, an accelerator controller, a torque rotating speed sensor, a hydraulic pump, a pressure flow rate collecting unit, a proportion overflow valve, a microprocessor and a control computer, wherein the two ends of the torque rotating speed sensor are respectively connected with the motive power source and the hydraulic pump, the installing positions of the pressure sensor or the flow rate sensor comprise a hydraulic pump oil outlet and a proportion overflow valve oil inlet, and the torque rotating speed sensor, the pressure flow rate collecting unit, the accelerator controller, the proportion overflow valve and the control computer are respectively connected with the microprocessor. The oil outlet pressure or the flow rate of the hydraulic pump is controlled by the proportion overflow valve for simulating the load change of a hydraulic motive power system of the engineering machine, and the precise simulation on the transient conditions of the hydraulic pump hydraulic load and the motive power source motive power load of the engineering machine in the actual operation process is realized, so the precision, the consistency and the reproducibility of test experiments are improved.