The hulushan gulf crossing narrow bridge locates in the southwest of dalian urban of Liaoning province. The mid-span of main bridge bridgings over offing 80 meters and the main bridge adopts 30+100+30 meters flying bird mid-support arch bridge form. There exists typhoon during construction, which makes construction difficult. It is necessary to analyze the safety of formwork scaffold and construct platform because of the complex structure and bad weather. The stability and strength of formwork scaffold and construct platform structure is evaluated through numerical analysis. The result verify that the formwork scaffold and construct platform structure satisfy the demand of code and are designed logically.