The design and application method of relocatable D-STATCOM are presented for distribution network power quality control purpose. Without transformer， the main circuit based on cascaded H-bridge inverter is used in the method. The compensation principle is analyzed according to a mathematical model. The parameter design of cascaded unit is based on the calculation of connecting voltage level and the equipment capacity. The optimal economic capacity is another important factor which should be considered during parameter design. Compact design of the compensator is implemented by using level power electronics unit of the power module. The inverter cabinet design is based on stratified and sub-phase principles. With these methods the whole system is integrated in a container to facilitate movement of the device. As an example of its application in Jiangxi power grid， the detailed parameter configuration of the relocatable D-STATCOM is given. By implementation of hierarchical classification protection method and the frequency divided control method which combines phase-shift SPWMs， the effectiveness of the proposed method is validated with satisfactory results.