The formation configuration design of the distributed spaceborne interferometric SAR (DSInSAR) is the key issue of the system design. The system performance optimization and formation flying orbit dynamic characteristic are its two basic restrictions. The DSInSAR has the characteristic of bistatic, squint and spatial baseline. As an example, a master transmitter satellite and multi receiver satellite system is analysized. The relation of height-measure accuracy and baseline vector is established. The relation between the differences of the two satellite orbit roots and baseline vector is set up too. So the baseline vector can be expressed by root difference. A formation designing rule that optimal height-measure accuracy can be acquired in the middle time of the system working is presented. Base on this rule, a design method of the two satellite and multi-satellite formation is presented. Simulation shows that the height-measure accuracy value of the optimal formation configuration is prior to that of interferometric cartwheel and pendulum.