As friction

wear and slap of pistons has adverse impact on the comprehensive performance of the engine

the early abnormal wear phenomenon of a small gasoline engine piston was studied. By building a dynamics simulation model of piston

the impact factors of slapping and friction were analyzed. A method of optimizing the key influencing parameters of piston friction and slap characteristics by using response surface model is proposed. To improve piston friction and slap characteristics

the multi-objective optimization model is established by taking piston profile

cylinder clearance

piston pin offset and crankshaft offset as optimization design variables

and taking the minimum value of kinetic energy peak value and the minimum friction loss as optimization objectives. The optimization results show that the optimized design parameter matching can reduce the friction loss of piston group by 9.13% and the maximum slap energy by 29.20% under the maximum torque condition of the studied engine. Finally

the bench test is carried out in the optimized prototype. The test results show that the engine power

torque and mechanical efficiency averagely increase by 2.37%

2.54% and 2.06% respectively， while the fuel consumption rate decreases by 1.19% on average and the wear condition of the piston was improved.