In order to solve the problem that the series Venturi tube only plays a role in a single stage, while the parallel Venturi tube occupies a large space and the cavitation performance is poor in industrial application. A new type of built-in Venturi tube was proposed and numerical simulation was used to study the cavitation characteristics of the structure. The effects of inlet pressure, inlet angle, outlet angle, throat diameter to pipe diameter ratio, throat diameter to throat length ratio and other parameters on the cavitation performance were studied. The research results indicate that as the inlet pressure increases, the area of cavitation inside the tube gradually increases. When the pressure reaches 0.7 MPa, the cavitation performance inside the Venturi tube reaches its maximum. By studying the different structural parameters of the internal small Venturi tube, it was determined that the cavitation performance of the new type of built-in Venturi tube reaches its maximum when the inlet angle is 40°, the outlet angle is 18°, the ratio of throat diameter to pipe diameter is 0.6, and the ratio of throat diameter to throat length is 2. This study can provide some reference for the design and application of a new type of built-in Venturi tube.