In order to reduce the load deviation,transmission error and meshing impact caused by meshing misalignment in helical gear transmission,a composite modification method of helical gear considering meshing misalignment was studied,and the variation rules of tooth meshing performance under different misalignment amount before and after modification were discussed.Based on the meshing contact calculation model of helical gears and performance indexes such as tooth surface load distribution,transmission error and meshing impact,the compound modification of spiral angle modification and tooth profile drum modification was carried out.The results show that the proposed compound modification can be used to effectively improve load deviation caused by meshing misalignment,and it is significantly superior to the single spiral angle modification in reducing peak-to-peak value of transmission error and improving meshing impact.