Abstract: According to the statistics of transmission lines in China in recent years, the fault caused by bird activity has become the third major transmission line tripping after lightning and outsize destroy. In this paper, the bird species and habits related to bird faults in overhead transmission lines are studied and analyzed. The types of faults related to birds, bird species and regional distribution are confirmed. Through the statistical analysis of bird related faults, it is found that the main fault occurred in the farmland or the low altitude adjacent to the water from March to July. At the same time, the probability of the occurrence of bird fault is also related to the structure of tower, the arrangement and the phase of the transmission lines. On the basis of the bird fault test and simulation calculation, the protection range of different bird faults under different voltage levels is obtained. Besides, the performance, advantages and disadvantages of different protection devices are compared. The reasonable prevention and control opinions are proposed in the paper.