Abstract: Objective Influence of additional structural stress caused by structural restraint of pipe boiler system on creep behavior of tee welded joints were investigated. Methods Creep evolution process of tee welded joints of P92 steel was simulated by finite element method. Results The results show that axial tensile/compressive structural stress significantly increases creep deformation of fine grain heat affected zone (FGHAZ) of the pipe, and effect on outer wall of the pipe is significantly greater than that on the inner wall. Due to the support of branch pipe, bending moment has little effect on creep deformation of FGHAZ on the inner wall of tee welded joints, but it can significantly reduce creep deformation of FGHAZ on the outer wall. Torque can reduce creep deformation of the outer wall of the pipe to a certain extent, but it will seriously aggravate creep deformation of the inner wall of the pipe, especially FGHAZ. Under the action of 30 MPa×W_t (W_t is bending section modulus of main pipe) bending moment, equivalent creep of FGHAZ on the outer wall of main pipe on the branch pipe side and the non-branch pipe side are decreased by 40.0% and 78.3%, respectively, compared with that without structural stress. Under the action of 30 MPa×W_n (W_n is torsional section modulus of main pipe) torque, equivalent creep strain of FGHAZ on the inner wall of main pipe on the branch pipe side and the non-branch pipe side are increased by 93.9% and 110.5%, respectively, compared with that without structural stress. Conclusion In the life assessment of tee welded joints of P92 steel, influence of structural additional stress should be taken into account.