The spallation target is an important component of the Chinese Initiative Accelerator Driven Sub-critical System(CIADS). The Lead-Bismuth-Eutectic(LEB) is used as the target material for spallation reaction and coolant of the target. The heat removal from the target window is a big challenge. The thermal-hydraulics design of the LBE spallation target system were done, including the target zone and the sub-system of heat removal. Commercial CFD software FLUENT was used to simulate the flow field and temperature distribution in the target zone. Some 3-D target models with single entrance, double-entrance and four-entrance were built to analyze the flow field of the full-size target tube. An LBE target loop with outside pipe, pump and heat exchanger was designed. An electromagnetic pump was chosen to drive the LBE target loop. The best-estimated thermal-hydraulic code RELAP5 was used to simulate the loop. The results showed that the design of the LBE target system is feasible from the point of view of thermal-hydraulics.