Municipal reclaimed water is used as supply water for boiler make-up water system in power plant, whereas the pre-desalination system has serious pollution and plugging in winter. The municipal reclaimed water quality, along with the fouling composition of pre-desalination system, were analyzed so as to figure out what leads to the fouling. The obtained results show that the system fouling is mainly microorganism breeding, which is caused by the municipal reclaimed water comprising several excessive components, such as COD, BOD and NH₃-N. In order to ensure high efficiency and stable of the boiler make-up water treatment system, the process of BAF(biological aetated fiter) or MBR(membrane bio-reactor) can be used to construct the advanced treatment system, which could improve the water quality.