The measurement of trace elements in water samples is a fundamental laboratory work for element transport in both soil and runoff.It is usually done by using a flame atomic absor ption spectrophotometer.Howerer,an extraction procedure by adding methyl butyl ketone(MIBK, for short) is necessary when the element concentration in the samples is very low.An improvement on the method is made by using concentrated water sample in order to increase the concentration of trace elements in the samples.The interfering problem of silicone on the concentration is solved by adding calcium chloride.The results show that the improved method is simple,and both the recovery rate of the samples and the accuracy of the method are satisfactory.