Abstract: FAAS was applied to the determinations of cobalt in surface water and waste water.Methods of pretreatment of different kinds of samples were described in detail,and the working conditions of the instrument were studied and optimized.Detection limit (3s/k) of the method found was 0.01 mg·L-1.The proposed method was applied to the analysis of samples of surface water and waste water,values of recovery found by standard addition method were in the range of 86%-104% and values of RSD′s (n=6) found were in the range of 1.3%-16%.