Reusing municipal sewage as boiler make-up water in Thermal Power Plant has become one of the mostly schemes to mitigate the shortage of water all over the world. the Influence of secondary effluent water quality on RO in reclaimed water advanced treatment technology cannot be ignored. Dissecting analysis of the fouled reverse osmosis membrane module from reclaimed water reuse system in thermal power plant was conducted through pressurized dye test, apparent observation, LOI and by using SEM-EDX and GC-MS. The results showed that the foulants deposited on the membrane surface contained large amount of organic substance such as the functional groups based  on alkyl and R-COO,and small amount of inorganic materials such as SiO2. The foulant consumption increased from the inlet of the module to the outlet,the variation of the inorganic is the same as this,while that of organic is on the contrary. The results obtained from the tests indicate the pretreatment system, scale and microorganism control are absolutely normal.