Abstract: A hingeless arch bridge of variable cross|section,catenary|box type has presented serious damage and deformation process before the controlled blasting,stability analysis on the object part and processing strength is carried out.Practice shows that pretreatment analysis on the bridge is helpful to the implementation of blasting and can guarantee the safety of construction to the full extent.The paper carries out the comparative analysis on several models and plans and finalizes the rational blasting plan and short delay detonation sequence.;