In order to reduce the fuel consumption and pollution of diesel engines,an efficient method of energy saving and emission reducing was presented.The working process of the diesel engines was improved through three ways,including magnetization process of diesel fuel before using,lubricating oil improving and exhaust gas treatment.By setting up a diesel engine test bench with the functions of fuel consumption measuring and exhaust gas analysis,the effect of these technologies used on the energy saving and emission reducing of diesel engines was explored.The results show that after magnetization of the fuel by using controllable magnetizer,under condition of medium load,the effect of less fuel consumption is more obvious,and the emission of smog is also reduced.Lubrication oil with excellent performance can effectively decrease friction coefficient and reduce fuel consumption of diesel engine.Reducing exhaust emissions with solid particles can be realized by using solid particle purifier,so the purpose of emission reducing is achieved.