Powder coatings are used in many fields because of their unique environmental friendly characteristics and excellent coating effect，but the commonly used electrostatic spraying process will produce a large amount of dust and high maintenance costs. In this paper，a study on water-borne coating process of powder coatings was described，and the effects of different defoamers and different baking systems on the epoxy polyester powder coatings were investigated. When the blending ratio of water to powder was（0. 65-0. 75）∶1， the coatings test sample with 1. 5% silicone oil defoamer was dried at 60 ℃ for 3 minutes，then temperature wasrised at 10 ℃/min to 180 ℃ and cured for 15 minutes，which could meet the requirements of HG/T 2006—2006 standard，and the performancewas basically the same as with electrostatic spraying process. The water-based coating method of powder coatings was characterized by its short-time process，simple equipment，convenient operation and no dust pollution. It is an environmentally friendly and effective coating process.