A type of three-pitch fluctuating speed ratio limited-slip differential (TPLSD) is presented for the first time,analyzed its working principle,introduced the tooth profile design method of using non-involute tooth profile and separated tooth profile design along the pitch line. Performance comparison between vehicles equipped with three-pitch fluctuating speed ratio limited-slip differential and common open differential is finished. The data from experiments prove that three-pitch fluctuating speed ratio limited-slip differential can increase the traction of a vehicle,improve its acceleration performance,decrease braking distance and limit sideslip. The basic structure of new differential is the same of open differential,the only difference is that they have different tooth profile,so the new differential has a high performance price. A type of three-pitch fluctuating speed ratio limited-slip differential (TPLSD) is presented for the first time, analyzed its working principle, introduced the tooth profile design method of using non-involute tooth profile and separated tooth profile design along the pitch line Performance comparison between vehicles equipped with three-pitch fluctuating speed ratio limited-slip differential and common open differential is finished. The data from experiments prove that three-pitch fluctuating speed ratio limited-slip differential can increase the traction of a vehicle, improve its acceleration performance, decrease braking distance and limit sideslip. The basic structure of new differential is the same of open differential, the only difference is that they have different tooth profile, so the new differential has a high performance price.