The structural deformation of sprinkler nozzles caused by long-term erosion and wear is one of the main reasons affecting the nozzle hydraulic performance. In order to explore the law of erosion deformation of nozzles and the effect of deformation on their hydraulic performance, based on the erosion coupled dynamic mesh method, a numerical model of solid-liquid two-phase flow of nozzle was established using standard k-ε turbulence model and Generic erosion model with the PY1-20sh nozzle as the research object. The numerical simulation of nozzle erosion deformation within 160 h was carried out on three groups of inlet flows under different sediment concentration conditions. The results show that the erosion wear mainly occurs at the main nozzle, and the continuous erosion wear reduces its mass, which in turn causes the uneven outward expansion of the pipe wall and the increase of the outlet diameter of the nozzle. The degree of deformation is positively correlated with the service time and sediment concentration, the deformation rate slows down with time, and the enlarged shape coefficient indicates that the shape of the outlet section gradually deviates from the circle. The change of nozzle hydraulic performance is characterized by increased outlet flow but decreased flow coefficient due to erosion deformation. The theoretical analysis shows that the range of the nozzle is gradually shortened, and the diameter of the water drop at the end is gradually reduced within a small range. The research results can provide a reference for the rational use and structural design of nozzles.