The performances of organic semiconductor thin film devices are largely determined by the transport properties of the organic-organic (OO) interfaces，but many present theories concerning charge transport at OO interfaces are not suitable for practical device modelling. Based on the Miller-Abrahams formalism for hopping conduction, an analytical model for charge transport at OO interfaces has been developed by considering the difference between OO interfaces and metal-organic interfaces. The result shows that the transport of carriers at an OO interface depends not only on the energy barrier of the interface, but also on the carrier concentration and the electric field at the two sides of the interface. This model can be used to self-consistent calculations of the current density, field distribution and other characteristics in multiplayer organic semiconductor devices.