As the core of industrial control, servo drives have become evident in small volume, multi-spindle integration, acclimatization and energy conservation in recent years. The main domestic and foreign servo drives adopt module temperature detection, thermal accumulation - heat dissipation model or inverse time overload algorithm. The overload multiple and time are relatively fixed, and cannot further improve overload capacity according to the environment temperature or load condition. Due to the low utilization rate of the radiator, the servo drive selection usually amplifies the first gear and increases the cost of the electrical system. Without adding energy feedback cells or capacitors, it’s not efficient to recycle the energy produced by braking. This paper mainly studies the overload algorithm which based on junction temperature prediction. The overloading algorithm can increase the overload capacity by 40%. Fanless design can be realized to meet the application of negative conditions such as conductive dust, cutting fluid and cotton. In general, the overload algorithm which based on junction temperature prediction is suit for the application of printing, packaging, semiconductor silicon, forging, laser cutting machines.