The invention discloses a camshaft structure arranged on top of a diesel engine, which comprises a cylinder cover, a camshaft body, a camshaft bearing seat, a pump nozzle, a transmission gear installed at the end of the camshaft, an air inlet cam and an air exhaust cam. The air inlet cam and the air exhaust cam are arranged on the camshaft body, the camshaft body is installed above the cylinder cover through the camshaft bearing seat and is also provided with an oil supply cam arranged on a drive pump nozzle, and a shock absorber used for subtracting torsional vibration is also arranged at the end of the camshaft, at which the transmission gear is installed. The invention ensures that the diesel engine has favorable fuel economy and power performance, enhances the combustion efficiency, reduces the combustion noise, enhances the tensile strength of the camshaft, and accords with the requirements of the power performance and the reliability of matching diesel engines of various industries including the universal industry, the ship industry, the agricultural industry, the power generation industry and the construction machinery industry, reduces harmful emissions in waste gas to enable the waste gas to reach emission standards of Europe III, Europe IV, further improves and enhances the emission index requirements and satisfies more and more strict environmental protection emission regulation.