The temperature load has a significant impact on the stress and deformation of bridge-mounted ballastless track structures during service. The temperature characteristics of ballastless track structures on bridges were investigated, which can provide theoretical basis for temperature load values in track structure design and service performance analysis. By examining the CRTS Ⅰ slab ballastless track-bridge system in Northeast China's cold regions, a refined temperature field model was developed, integrating geographic information and temperature change simulation. Dynamic boundary conditions, driven by meteorological big data, were used to account for the east-west asymmetric radiation characteristics of the track. The temperature characteristics of the track slab and cement asphalt (CA) mortar layer, including vertical temperature gradient loads, were analyzed and compared with those of ballastless track-subgrade structures. The effect of different substructures on the temperature load of the track system was also explored. The results indicate that the simulation method used can provide reliable calculations for the temperature field of track structures on bridges. The overall temperature service range for the bridge's ballastless track slab is -34 ℃ to 50 ℃, while the CA mortar layer ranges from-23 ℃ to 35 ℃, and the base slab ranges from -15 ℃ to 23 ℃. The positive temperature gradient loads for the bridge CRTS Ⅰballastless track slab and CA mortar layer are between 0 and 93 ℃/m and 0 and 275 ℃/m, respectively, while the negative gradient loads range from -43 ℃/m to 0 ℃/m and -170 ℃/m to 0 ℃/m. The CA mortar layer experiences larger cyclic daily temperature gradient loads. Compared to the ballastless track-subgrade structure, the bridge-mounted ballastless track structure exhibits greater temperature gradients, with the maximum positive temperature gradients for the track slab and CA mortar layer increasing by approximately 6% and 16%, respectively, while the maximum negative gradients increase by about 5% and 32%.