The invention provides a variable-length engine connecting rod. The variable-length engine connecting rod comprises a connecting rod large end and a connecting rod small end; the connecting rod largeend comprises a connecting rod tilting fillet, a tilting fillet guide rail and an oil cavity; the connecting rod large end and the connecting rod small end are connected, the connecting rod tilting fillet is arranged in an oil cavity of the connecting rod large end, the connecting rod tilting fillet divides the oil cavity into a first oil cavity and a second oil cavity, and the connecting rod tilting fillet slides on the tilting fillet guide rail in the connecting rod large end. According to the variable-length engine connecting rod, the changing between the center distances of the connectingrod large end and the connecting rod small end can be achieved, the connecting rod tilting fillet in the connecting rod large end achieves sliding displacing through oil pressure, the structure is simple and reliable, membrane springs are integrated in a cover plate, and the effects of increasing foundation damping, wear resistance and seal lubricating oil are achieved.