Thermoplastic composite pipes are considered to be the next riser design generation for deepwater and ultra-deepwater offshore oil field development, due to its corrosion resistance, low weight, high strength, adequate flexibility, low permeation and high fatigue life. Thermoplastic composite pipe typically consists of polymeric (e.g. PEEK) and composite laminate (e.g. carbon/glass fibers) layers. This paper presents a theoretical analysis of thermoplastic composite pipes under pure torsion combined with thermal loading, considering the inner and outer isotropic homogeneous polymeric layers and intermediate transversely isotropic laminate ply layers. All layers are assumed perfectly bonded, and the interface continuities are considered. The theoretical model is validated by a finite element model, followed by linearity behavior analysis of combined mechanical and thermal loading conditions. The stress and strain states, rotation and displacements under pure torsion combined with thermal loading are analyzed. The axial, hoop and shear stresses are carried predominately by the laminate, while the radial stresses are negligibly small. The torsional stiffness of TCP decreases with increasing temperature. In addition, the torsional stiffness decreases slightly subjected to higher applied rotation under a given temperature distribution.