This research is to decomposition of persistant and bioaccumulative perfluorooctanoic acid(PFOA) in water with activated-carbon catalyzed persulfate (S2O82-) under ambient temperatures. The main objective of the usearch was of investigat the effect of temperatures (25, 35 and 45oC), initial pH (2.5, 7.0 and 11.0), and the persulfate doses and activated-carbon doses on the PFOA decomposition study. Three different system were studied: Persulfate (PS) only system and active-carbon (Ac) only system and PS+AC system. The result showed that the PS+AC system has a better decompostion capability than that of PS only system. But the AC only system could remove more perfluorooctanoic acid from water, it did not decompose perfluorooctanoic acid. The best operation for the PS+AC system is high temperature coupled with low pH, which can accelerated the free radical (SO4-˙) generation, to decompose PFOA. At pH of 2.5, temperature of 45 oC, PS dose of 60.25 mM, AC dose of 1g/L, and shake rate of 100 rpm, 85% PFOA were decomposes and 79% of fluoride-ions were released to the water. Experimental of the PS only system could be simulated with pseudo first-order kinetics of the PFOA degradation; while those of the PS+AC system and the AC only system could be well simulated with pseudo second-order kinetics.