Abstract: Calculating transverse distribution coefficient of vehicle load on precast prestressed concrete hollow slab (PPCHS) bridge is one of key problems for the design of widened bridge, whose existing exterior slab and deck are connected to the adjacent new slab and deck. On the basis of hinge-jointed slab theory and mechanical method, the general force equations for hinge-jointed slab method are deduced, which may be used for calculating load transverse distribution influence line of PPCHS bridges with slabs in different cross-section, space or material properties. For a normal PPCHS bridge and a widened bridge, the corresponding computing program is completed and the most unfavourable position and transverse distribution coefficient of load are calculated. The allowable value of transverse distribution coefficient of the old PPCHS is determined by comparing vehicle loads specified in old and current codes, which can be used to judge whether the slabs should be strengthened. Slabs to be enhanced in the transverse connection are determined by observing the variation of their transverse distribution coefficients.