A new kinetic theory for granular flow with particles of different mass and density is developed in the present study. The solid particles are considered as smooth, and nearly elastic spheres. It is assumed that exch species in the mixture have different density and size. The complete pair distribution function for two colliding spheres is assumed as the product of the spatial pair distribution function (Gidaspow 1994) and the two single-particle velocity distribution functions. The constitutive relations together with transport equations form a model for granular mixture of particles of different density. The computed results indicates significant changes for different properties of multi-phase flow such as viscosity, pressure etc.