Aiming at the 15T gasoline engine connecting rod assembly processing,three processing methods were tried to solve the problem of long oil hole machining.Through comparing the processing effects of the three processing methods,CNC deep hole drilling was selected which had stable product quality,high efficiency and minimum cost.Aiming at the key technical problems encountered in the processing,such as heat dissipation, chip removal, guiding device, poor rigidity and gun drill life,indepth analysis and research were made and the effective solution was put forward.