In order to study the erosion behaviour of the gooseneck pipe in the drilling fluid environment and the evaluation of the surface strengthening effect, the influence of the drilling fluid density on the erosion behaviour of the gooseneck pipe and the evaluation method of the surface strengthening of the inner lumen were investigated by the finite element simulation and analysis method. The results show that: the erosion rate of gooseneck pipe is the largest in the inner diameter of the bend, and the maximum erosion rate becomes larger with the density of drilling fluid becoming higher, but the maximum erosion rate still occurs in the inner diameter of the bend. The maximum deformation displacement can be effectively reduced by 34.23% after surface strengthening of the inner lumen of the gooseneck pipe. It can be seen that the effect of drilling fluid density on the erosion behaviour of the gooseneck pipe cannot be ignored, and surface strengthening can effectively reduce the maximum deformation displacement.