In recent years, petroleum and natural gas industry technology continues to develop, so the market demand for polyester fiber reinforced flexible composite pipe is increasing. Polyester reinforced flexible composite pipe is widely used in practical production, which is based on thermoplastic material and winded by polyester fiber. Based on the anisotropic uniformity of polyester reinforced flexible composite pipes, this paper focuses on the mechanical behavior of flexible composite pipes under internal pressure. By using numerical analysis method, the stress-strain change and burst pressure model of polyester reinforced pipe under internal pressure are established. The short-term burst pressure test is carried out to obtain the burst pressure of the reinforced pipe. The finite element analysis software ABAQUS is used to establish finite element model for simulation analysis. According to the generated test data, the correctness of the finite element analysis results is verified. The sensitivity of winding angle and diameter-thickness ratio to the pressure was studied to further understand the mechanical properties of polyester reinforced composite pipe.