A sensitive method for the determination of trace copper(II) after the preconcentration by adsorbing its cupferron complex onto microcrystalline benzophenone was developed.Several experimental conditions such as the pH of sample solution,concentration of cupferron, amount of benzophenone and atirring time were optimized. Trace compper(II) in 100mL solution was chelated with $3.0;{ imes};10^3$ M cupferron at pH 5.0. After 0.20g benzophenone, The benzophenone adsorbing Cu-cupferron complex was filtered and then Cu-cupferron complex was desorbed in 10 mL ethanol. Copper was determined by a flame atomic absorption spectrophotomethry. The interfering effects of diverse concomitant ions were investigated. Fe(III) interfered seriously with, but the interference by Fe(III) was completely eliminated by adjusting the concentration of copferron to $5.0;{ imes};10^3$ M. The detection limit of this method was 8.6${ imes}$10 M(5.5 ngmL$^1$). Recoveries of 97% and 96% were obtained for Cu(II) in a stream water and a brass sample, respectively. Based on the results from the experiment. this proposed technique could be applied to the determination of copper(II) in real samples.