By using the methods of stack,cross correlation and interpolation of Qilian Mountains active source network data processing,we analyzed the air-gun travel time variation characteristics of phase P-wave and S-wave of the January 21,2016 Menyuan M_S6.4 earthquake,Qinghai. The results show that about 6 months before the earthquake,the relative time of three stations near the epicenter showed a decline(travel time decrease)and low the value anomaly returned to normal about 3 months before the earthquake. After that there appeared a travel time decrease,and the earthquake occurred in the recovery process. The maximum decrease of S-wave travel time was 18ms,and the change of travel time after the earthquake was normal. The variation trend of the 3 stations is consistent,among which the S-wave travel time is the most obvious at Station ZDY38 which is closest to the epicenter. The variation of travel time is smaller at the farther stations and is related to the regional stress accumulation. The shortening of travel time means the increase of the velocity.