Recently,Cloud point extraction (CPE) has become an attractive area for the separation and preconcentration of trace metal ions [1].The principles of CPE have been illustrated in some interesting reviews [2].Cobalt is an essential trace element in human body.It is known that the toxicity of Cobalt is quite low,but high exposure to this element can cause the diseases such as asthma and skin irritation [3].Therefore,to determine of trace amounts of cobalt becomes significantly important in the fields of environmental analysis,process control and medicine [4].