To promote the engineering application of the new spread hollow slab bridge system, a calculation method for lateral load distribution factors was proposed. The beam spacing, span length, bridge width and beam depth were selected as key parameters affecting the lateral load distribution behavior of bridge structures. Finite element models for bridge configurations with different parameter combinations were established using the ABAQUS software, from which moment and shear distribution factors were determined for one-lane and multi-lane loaded cases and effects of aforementioned parameters were analyzed. Furthermore, design formulas of moment and shear distribution factors were obtained via the nonlinear regression analysis method. Comparisons with test results of a practical bridge indicate that proposed formulas are reliable and applicable for structural designs of spread hollow slab bridges in the engineering practice.