With the rapid development of economic level, people's requirements for environmental facilities for leisure and entertainment are constantly improving. The water environment of swimming pool is directly related to people's safety and health. Therefore, it is necessary to improve the quality of swimming pool water and give people a safer and more comfortable swimming environment. The photocatalytic assembly was numerical simulated with different internal structures using computational fluid dynamics(CFD) numerical simulation software. The simulation results show that the radiation flux of scheme 14B (shell diameter of 200 mm, 14 quartz tubes, quartz tube diameter of 30 mm, inner center distance of 28 mm, outer center distance of 76 mm) is evenly distributed. When the inlet flow is 12 m³/h, more than 90% of the velocity is greater than 0.1 m/s, reaching a turbulent state which is conducive to mass transmission, promotes photocatalytic reaction and improve the sterilization effect. The inlet and outlet position of the end cavity has little effect on the fluid in the component, and its position can be determined according to the site installation requirements. The radiation field is evenly distributed when the minimum basic unit of the quartz tube in the component is positively triangular cycle distribution and the center spacing of the inner tube is 52 mm. The results provide technical support for the development of swimming pool water sterilization equipment and lay the foundation for the development of the industry.