Abstract: Based on the second bridge of jialing river bridge in cangxi county, Midas Civil was utilized to simulate the process of construction and we analyzed the influence rigid frame's continuous length on structural line in continuous rigid frame bridge's construction, It is found that the cantilever structure will be deformed under the action of self weight and prestressing force.In the case of ignoring the time factor, if the cantilever length is short the structure will bend upwards.Because the influence of prestressed load on deflection is greater than that of self-weight. As the length of the cantilever increases, the influence of self-weight on deflection is increasing. When reached 4/5 of the largest cantilever length, the structural deformation is changed from the top to the bottom.