Abstract: High voltage direct current（HVDC）transmission line has a long distance,great differences in terrain,geomorphology,environment and climate.It has high probability of failure and needs high accuracy for fault location.So,the wave equation describing the electrical characteristics of the distributed parameter line is put forward,which is the basis of fault location principle.According to the time,frequency and space,the traveling wave methods,natural frequency methods and fault analysis methods are summarized.It makes clear that the main fault location method in real application should be traveling wave method,and the others assist to improve the reliability of overall fault location.Then,the follow-up ideas and programs to improve several existing problems are also presented,such as pickup in high resistance grounding fault,oscillation of initial wave head,and frequency change of reflection coefficient.