Abstract: To select the process for source water with organic micro-pollution,the annual changes of organic content,specific ultraviolet absorbance(SUVA),disinfection by products formation potential(DBPFP),molecular mass distribution,taste and odor were all analyzed in a micro-polluted reservoir,which took water from the downstream of the Yellow River.Resultsshowed that the organic contents changed slightly throughout the year,and the average of oxygen consumption,UV₂₅₄,DOC were 2. 32 mg/L,0. 045 cm^-1,2. 32 mg/L,respectively. However,the SUVA was higher; small organic molecules was the most,mainly to 70% of it(< 3 ku); DBPFP was also higher,and THMs accounted for 94. 6% of DBPFP,with CHCl₃ accounted for 77%. The 2-methylisoborneol(2-MIB) concentration changed with season,which accorded to the alcohol content and metabolized by Cyanobacteria,such as Planktonema,Oscillatoria,etc. The organics characteristics of the reservoir water were associated with HRT of the process of sand setting,storage from the Yellow River and its sources of organic matters. Ozone biological activated carbon process was appropriate to be used for treatment.