An engine performance testing and comparing apparatus, comprising a connecting component coaxially connected to a flywheel (1) and outputting a torque, a torque transferring sensor (2) coaxially mounted on the connecting component, a processing device provided at the periphery of the sensor (2) and paired with the sensor (2), and a load-connecting transmission shaft component coaxially mounted outside of the sensor (2). The engine performance testing and comparing apparatus is structurally reasonable, quick to mount, quick and accurate in testing, economical and practical, of a short assembled length, and structurally compact, effectively saves mounting space, allows stable and reliable torque transfer, and has high torque transfer efficiency.