Abstract: Converted wave exploration can obtain abundant information in gas-bearing horizon. The pre-stack migration of converted-wave is more complex than that of P-wave because the ray paths of the converted-wave are asymmetry. In VTI media, the travel time of 3-D pre-stack Kirchhoff time migration for converted-wave is affected by many factors, including migration aperture, velocity model, and two-way vertical travel time. Aiming at this problem, we discussed the calculation method and migration algorithm of converted-wave travel time. The travel time includes the P-wave travel time from the source to imaging points and the converted-wave travel time from imaging points to receivers. The travel-time form is established to improve the migration computation efficiency and guarantee the accuracy of travel time. In addition, we also discussed the algorithm for 3-D pre-stack time migration of converted-wave in VTI media. The validity of pre-stack time migration method is verified by a theoretical model. The 3-D pre-stack migration result of one actual converted-wave data from a certain oilfield in west area matches its logging data very well and the imaging effect in gas-bearing horizon is better than that of P-wave.