The objective was to analysis the fluid characteristics of ball valves with different valve spool structure.Flow analyses were carried out using Fluent, the variety of pressure drop and flow coefficient against valve opening with different core gap of valve were achieved.Based on the mathematical model，a simulation model was built in MATLAB/Simulink. The simulation results show that the use of triangular and round opening in valve coreinstead of initial valve core can make the flow of whirlpool in the downstream improved, the flux variety linear is benefited from the gap shapes used in vavle.