The collapse and buckling behaviors of reinforced thermoplastic pipe (RTP) under external pressure are studied in this paper. A theoretical model which includes axial and shear deformation is applied based on the model initially proposed by Kyriakides and his coworkers. Simulation of the reinforced layers of RTP is simplified using equivalent stiffness method. The load–displacement relation of RTP under external pressure is obtained based on the theoretical model. A three-dimensional (3D) finite element model (FEM) is also built to simulate the response of RTP using the software abaqus. Numerical simulation results from abaqus are similar to those from theoretical model. Besides, external pressure tests for RTP are carried out and the test results are compared with the analyzed results. Finally, factors that influence the external pressure capacity are also studied.