The invention provides a system for detecting mass, mass center and mass offcenter of a cylinder, and belongs to the measurement technical field. The system for detecting the mass, the mass center and the mass offcenter of the cylinder comprises a main controller, a data acquisition module, a control interface module, a signal conditioning circuit, a motor driving circuit, a distance measuring device, a power module, a lifting motor, four weighting sensors and a lifting platform. The cylinder to be measured is clamped on a tray at one time, the lifting motor is started, the tray is landed on the weighting sensors, the distance measuring device is moved to measure a reference distance of the cylinder, and then data of the sensors are acquired twice in a front and back mode when the cylinder rotates by 90 degrees, and a detecting result of the mass, the mass center and the mass eccentricity of the cylinder can be acquired according to a four-point method. The system for detecting the mass, the mass center and the mass offcenter of the cylinder has the advantages of being compact in structure, large in measuring diameter range, high in measuring accuracy and automation degree, and capable of being used in delivery detection, factory acceptance inspection and quality characteristic detection of cylinder parts or products.