Abstract: With the deepening of research, the low concentration gas - water mist two-phase fluid in the pipeline transportation technology are safely applied in coal mine. To detect pressure loss of the local pipe fittings in gas pipeline, numerical simulation and experiment research for gas - water mist pipeline at 90 ° elbow drop case was carried out. Numerical analysis shows that the two-phase fluid pressure drop increases with the increase of the speed at 90°elbow and decreases with increasing diameter of pipe and first decreases and then increases with the increase of bending moment ratio, the best bending moment ratio is from 2.8 to 3.2. 90°elbow pressure drop test verifies the effectiveness of the numerical simulation results.