An empirical equation to represent the complete stress-strain behaviour for unconfined permeable concrete with compressive strength ranging between 10-35MPa and porosity ranging between 25-15%, made with different combinations of aggregate size and sand ratios is proposed in this paper. A series of compression tests were conducted on 100 × 200 mm cylindrical samples using a modified testing method to determine the complete stress-strain behaviour of permeable concrete. Various existing models for low strength concrete and normal strength concrete were used and compared with the experimental data. Various parameters were studied and their relationships were experimentally determined. The only parameters need to run the model is the ultimate compressive strength and the density. The proposed empirical stress-strain equations were compared with actual cylinder tests results under axial compression, and demonstrated that the present model gives a good representation of the mean behaviour of the actual stress-strain response.