Abstract:The Henkou and Badu major bridges were constructed by the First Engineering Department of the Tunnel Engineering Bureau of MOR. The No. 3 span of Henkou Bridge and the No.4 span of Badu Bridge are the main spans both being the deck bridge with 2 × 64 m continuous steel truss. Taking the balanced cantilever erection method for the continuous prestressed reinforced concrete beam as reference,the bidirectional symmetric complete cantilever assembly method was applied and the successful results had been obtained. By using this erection method ,there were following advantages:the invested machineries being minimum,assembly works decreasing one half increasing another working area,shortening the construction period ,and having significant social and economical benefits.