We adopt spline subdomain method analyzing skew girder group and validating the inerrancy with Ansys,thereby it embodies the superiority of the spline subdomain method.

The construction method of spline function and the basic principle on spline subdomain method were described.

In this paper, the arbitrary quadrilateral slab bridges are analyzed by spline subdomain method, in which an arbitrary quadrilateral subdomain with curved sides which comes from the irregular bridge structure dispersion is transformed to a normal rectangular one by mapping of coordinates, the two dimensional spline is adopted to approach the displacement function of this subdomain.

The displacement mode is established by using generalized spline subdomain methods which has the advantage of fewer degrees of freedom and arbitrarily setting nodes.

Based on the concepts of penalty elements and unequidistunt B spline function, the spline penalty suboomain method is for the first time PUt forward here, so that the compatibility of displacements of the two skew suboomains of the combinative shell is well satisfied and the applied range of spline subdomain approaCh is developed.