Abstract: Active source two-dimensional transmission seismic wave velocity tomography is one of the most important methods for detecting geological structure in coal mining face. This method simplifies the space between two roadways into a horizontal plane and does not take into account the dip angle of coal seam. The Pseudo 2. 5 dimensional trans- mission seismic wave velocity tomography is proposed in this paper,the planar model of two-dimensional inversion is changed to a plate-shaped model,and the program is implemented. Through numerical simulation and field test,the travel time of transmission seismic waves in different inclined coal seam is obtained,and the 2 and pseudo 2. 5 dimen- sional seismic velocity tomography are realized. By comparing and analyzing the results of two tomography methods,it is found that the two-dimensional velocity tomography of transmission seismic waves has many errors in the detection of high dip coal seam. In the field test,the pseudo 2. 5 dimensional transmission velocity tomography method basically eliminates the influence of double roadways elevation,and the velocity anomaly area is more consistent with the geo- logical structure’s spatial shape and location. The ray tracing of the pseudo 2. 5 dimensional transmission seismic wave velocity tomography is more accurate,and the inversion results are closer to the true velocity of coal and rock.