Thequasi-chemical nonrandom lattice fluid model is capable of describing thermodynamic properties for complex systems containing associating fluids, polymer, biomolecules and surfactants, but this model fails to reproduce the singular behavior of fluids in the critical region. In this research, we used the quasi-chemical nonrandom lattice fluid model and combined this model with a crossover theory to obtain a crossover quasi-chemical nonrandom lattice fluid model which incorporated the critical scaling laws valid asymptotically close to the critical point and reduced to the original quasi-chemical nonrandom model far from the critical point. The crossover quasi-chemical nonrandom lattice fluid model showed a great improvement in prediction of the volumetric properties and second-order derivative properties near the critical region.