Due to the limited production, less permeability and low pressure of coalbed methane (CBM), a new kind of cyclone separator called backflow type dynamic cyclone separator (BDCS) was designed, which includes a dynamic impeller and a center return pipe. It can meet the requirements of the dust and/or liquid separation equipment used for surface gathering process such as high precision, low pressure and anti-flow fluctuation. This paper introduced the structure and working principle of the separator, as well as studying its flow field and separation performance. The research shows that BDCS has less pressure drop compared with the separator without return pipe. The decline rate of pressure drop is about 10% between the separators with or without return pipe. By adding dynamic impeller and return pipe, the efficiency exceeds 95% when the particle size is >5 mu m. The tangential velocity is decided by the rotating speed of the impeller and almost not influenced by the handling capacity. Therefore, the separator maintains high separation performance when the handling capacity changes from 2 x 10(4) m(3)/d to 3 x 10(4) m(3)/d. It indicates that the device had a good ability of anti-flow fluctuations. (C) 2016 Elsevier B.V. All rights reserved.