The Silurian Longmaxi Formation shale in Sichuan Basin is an important shale gas reservoir for shale gas exploration in China,but the anisotropy of Longmaxi shale is not studied sufficiently.In this case,the velocity anisotropy is examined under the reservoir pressure conditions by ultrasonic testing method.The variation patterns of wave velocity in different directions as a function of confining pressure are also presented.Mineral analysis and X-Ray scanning techniques are applied to reveal the affection factors in Longmaxi shale,the result shows the mineral layer and micro-bedding are the mainly factors of anisotropy.