Water and sediment movement in filter is complex and changeable. In the beginning, local blockage on filter element caused by non-uniform distribution of sediment affects flow distribution which will change tracks of follow-up sediment. Using CFD-DEM（computational fluid dynamics, CFD;discrete element method，DEM) method to simulate flow field and sediment distribution in Y-type screen filter, the resistance characteristics of filter and its influence on the movement and distribution of sediment were directly reflected. Results showed that the obvious backflow, vortex and viscous flow in the whole flow field led the uneven flow rate which was higher in outlet area and lower in inlet area, with a difference of 39%. Filter element was responsible for 90% of the total pressure loss. Flow condition was changed significantly with time, while sediment deposition appeared in the order of outlet under area, outlet upper area, inlet under area, inlet upper area and finally blocked the whole filter element. Among the four face areas in the filter element, sediment deposition was the least in outlet upper area which was at high flow rate while most in inlet upper area which was at low flow rate. So appropriately raising the flow section of outlet upper area with a better performance can improve the filtration efficiency.