Abstract: To investigate the interaction between the road-cum-rail three-pylon cable-stayed bridge with kilometer-level span and the track under complex environmental loading. The continuous welded rail (CWR)-cable-stayed bridge spatial coupling model was established considering the force transfer relationship between the bridge and the track. Analyzed were the effects of non-uniform temperature field, of static wind load, of moving train load and, of random highway load on the spatial deformation of bridge and on the mechanical and deformation laws of CWR. The results show that the vertical displacement of the bridge and the longitudinal additional force of the rail are proportional to the temperature under the cables temperature change. Considering the temperature difference between each member of the main beam, the stress and deformation of the rail are reduced. The static wind load makes a significant difference in the stress and deformation of the line on the facing and leeward sides. The daily wind speed has no significant effect on the horizontal irregularity of the track. The deformation of bridge and rail shows significant time-history characteristics and strong fluctuations with the movement of train load on the bridge, using the moving load series to study the effect of train load on CWR on kilometer-level span bridge is necessary. The randomness of automotive vehicles has no significant influence on the bridge-track interaction. It is feasible to still adopt the lane load in the code when calculating the deformation and force of the CWR on such kilometer-level span road-cum-rail bridges. The temperature variation of pylons and piers and random highway load have little influence on the beam-rail interaction. It is suggested that the mechanical behavior of bridge and track in the areas of mid-span, of pylon and, of bridge end should be paid more attention in the design and maintenance.