The work aims to study the problem of erosion and wear on four-way pipe by fluid carrying sand in heavy oil thermal production, so as to define the failure mechanism and characteristics. The metallographic analysis of ZG(J)35CrMo of the damaged four-way pipe was analyzed by metallographic analyzer, and the micro erosion morphology of the four-way pipe was analyzed by scanning electron microscope (SEM). At the same time, the erosion experiment of four-way pipe material ZG(J)35CrMo was carried out by the multiphase flow erosion tester, and the erosion prediction model was established and verified by the single factor erosion experiment. Finally, CFD-DPM-EPM (coupled computational fluid dynamics-discrete particle-erosion) numerical model was established to study the influence of different fluid velocities, particle size and mass flow rate on the erosion law of four-way pipe. The metallographic analysis result shows that the matrix structures of the material were sorbite, ferrite and bainite, and there is slight decarburization on the surface. SEM results show that the inner wall of the failed four-way pipe has obvious sand erosion morphology, and the material has no obvious deterioration and brittle fracture phenomenon. The erosion prediction model is verified by single factor erosion experiment, which proves the accuracy of erosion prediction model constructed by regression analysis method. With the increase of fluid velocity from 5 m/s to 25 m/s, the maximum erosion rate of the four-way tube increased by 16.947 times. When the particle size increased from 0.05 mm to 0.2 mm, the maximum erosion rate of the four-way tube decreased by 2.183 times. However, when the particle size increased from 0.2 mm to 0.4 mm, the maximum erosion rate of the four-way tube increased by 1.382 times. When the mass flow rate increased from 0.15 kg/(m2.s) to 2.4 kg/(m2.s), the maximum erosion rate increased by 16.584 times. The failure of the four-way pipe is mainly due to the erosion of the inner wall of the pipe by particles, and the four-way pipe can not bear the internal pressure after being thinned to a certain thickness. The shoulder of the exit section of the four-way pipe is a high-risk area of erosion, and the maximum erosion rate of the four-way pipe increases exponentially with the increase of the fluid velocity, and with the increase of particle size, the maximum erosion rate decreases first and then increases. When the mass flow rate increases, the maximum erosion rate increases linearly.