Abstract: The significant influence of the hygrothermal environment on the failure of the carbon fiber reinforced polymer (CFRP) composite-aluminum alloy bolted joints has threatened the safety of the overall structures. In order to accurately assess the influence of hygrothermal environment on the quasi-static failure of CFRP composite-metal bolted joints, a quasi-static failure prediction model of composite-metal bolted joints considering hygrothermal effects was established, based on the existing progressive damage analysis of composites and Ductile damage criteria of metal. This model is validated by good consistency between the numerical and experimental results of CFRP composite-aluminum alloy single-bolt double-lap joints under 23℃/dry and 70℃/wet conditions, respectively. The proposed model was further used to reveal the influence laws of different hygrothermal environments on the quasi-static tensile failure of CFRP composite-aluminum alloy single-bolt double-lap and multi-bolt double-lap joints. The research shows that the failure loads of the single-bolt double-lap joints under 23℃/wet condition, 70℃/dry condition and 70℃/wet condition are reduced by 4.5%, 7.2% and 13.9%, respectively, compared with 23℃/dry condition. The high temperature condition is the main factor that leads to the increase of the failure area above the CFRP composite laminate under hygrothermal environments. As the number of the bolt increases, the declining degree of the quasi-static failure strength under 70℃/wet condition decreases gradually compared with 23℃/dry condition.