Abstract: In the parabolic trough concentrating solar power plants,the multi-circuit flow distribution characteristics in the solar field have an important influence on the outlet temperature of the HTF（heat transfer fluid）and the operating performance of the plants. The traditional U-type solar field achieves its balanced flow distribution by regulating valves,which has higher requirements for the control level and higher construction cost. In this paper,parabolic trough solar field with molten salt as HTF is chosen as the research object,and a new Z-type layout of solar field is proposed,which realizes multi-loop self-balanced flow distribution by changing the diameter of the main-pipes. Through theoretical design and dynamic simulation based on Apros software,the steady state and dynamic performances of flow distribution,outlet temperature and pressure drop of the Z-type heat collecting loop under the change of DNI,inlet mass flow and cloud disturbance are studied. The results show that the Z-type solar field layout combined with the change of the main pipe diameter has good flow self-balance performance under both steady-state and dynamic conditions.