Abstract: With the improvement of the accuracy of ampacity calculation and the emergence of complex laying methods, the calculation and increase of cable ampacity have become the hotspots of cable research. Firstly, the correction factor method, thermal circuit method and numerical method for calculation of ampacity are introduced,and the research objects and methods are discussed. Then, the methods to increase ampacity are discussed, including the laying environment, the laying scheme and load distribution. Finally, the calculation andincrease methods of ampacity are summarized, and the future is prospected.