Based on the structural characteristics and design requirements of permeable brick, the paste thickness on coated aggregates was taken as the main mix proportion design parameter. To satisfy the strength requirements, the paste thickness on coated aggregates would be changed. The mix proportion design method will be as follows：firstly, the aggregate amount of unit volume permeable brick is fixed according to the aggregate packing density, secondly, the aggregate surface area is calculated according to the apparent density and particle diameter of aggregate, thirdly, the paste thickness on coated aggregates and mass ratio of water to cement are set, and then the paste volume and cement amount are calculated, finally, the workability of permeable brick mixture is adjusted by the superplasticizer. The test results show that the permeable brick mix proportion design method is feasible.