Connecting rod bearing bush includes connecting rod upper bush and lower bush, which are installed at the connecting part of connecting rod and crankshaft and play the role of wear resistance, connection, support and transmission. An oil groove is arranged on the inner cylindrical surface of the upper bush along the circumferential direction, the central angle corresponding to the oil groove is 80～120°, and an oil passing hole is arranged on the wall of the connecting rod bearing bush at the oil groove part. The oil groove with reasonable arc length is arranged on the connecting rod bearing bush, which ensures that the engine oil can supply oil to the piston at the most appropriate time and time during the working process of the engine, ensures that the piston cools well and avoids the wear and damage of the cylinder; The reasonable oil groove arc length can ensure the best oil supply, which can not only ensure reliable cooling, but also avoid the waste of oil and the negative impact of excessive oil on engine work; At the same time, the positioning protrusion arranged on the connecting rod bearing bush enables it to be assembled at a reasonable position, so that the oil groove part of the connecting rod bearing bush avoids the heavy load stress area and ensures that it is less worn when working.