The invention discloses an engine performance detection and comparison device comprising a connecting assembly being coaxially connected to a flywheel and outputting torque outwardly. The connecting assembly is coaxially equipped with a sensor thereon capable of transmitting torque, the periphery of the sensor is provided with a processing device cooperating with the sensor, and a drive shaft assembly connectable to a load is mounted coaxially on the outside of the sensor. According to the invention, the device has the advantages of reasonable structure, quick installation, quick and accurate detection, economy and practicality, short assembly length, compact structure, effective saving of installation space, stable and reliable torque transmission, high torque transmission efficiency.