To evaluate the behavior of cemented clay treated reinforced with copper sludge, 63 ultrasonic pulse velocity tests were conducted. The copper sludge content, curing period and moisture content were all varied so that the behavior of the sample could be examined. The cement content was 11% by weight clay. The copper sludge contents were 0, 5, 10, 15, 25, 30 and 35% by weight of the cement and samples were cured for 7, 28, and 60days. The results of this study can be used for estimating of the impacts of these variables on mechanical properties of cemented clay soil treated with copper sludge. The results of this study indicates that at early age of curing time inclusion of copper sludge decreases the ultrasonic pulse velocity. The ultrasonic pulse velocity of samples at 7 and 28days decreases by increasing copper sludge content. The ultrasonic pulse velocity of sample on the wet side is higher than wet side of the dry unit weight-moisture content curve. Moreover an optimum percentage for the copper sludge (%15) in which the behavior of cemented clay improves significantly.