An innovative, multi-stage solar distillation with slope-plate falling film system for seawater desalination is investigated. The system consists of a solar heater (flat plate solar collector) and one evaporation-condensation set that is composed of five slope-plate stages. On one side of a slope-plate, seawater is distributed by falling film to evaporate, whereas on the other side, the plate is heated by condensing steam generated in the previous stage. The mathematical model of the system was presented. The temperature of every stage plate, the water production rates of every partition and the total water production rate in different time were studied theoretically, and found that the system could produce about 35 kg/(dayÂ·m2) in June. It has proven to be an efficient device to utilize solar energy for obtaining fresh water.