Abstract: The non-linear equations governing wind-induced internal pressure responses for a two-compartment building with a windward dominant opening are derived based on some reasonable assumptions. The law of mass conservation, adiabatic equation, and the unsteady form of the Bernoulli equation are used for the derivation. Then, the improved method for the existing research result based on corresponding linear model is given. The numerical calculation results show that the effects of Helmholtz resonance on internal pressure responses have been neglected in the existing linear model, but it can be made up by the improved method proposed in this paper.