Abstract: The SoC IC generates much more power dissipation during testing which may cause reliability problem to the device.Hence, it is desirable to schedule the tests under the allowable peak power constraint.This work presents, based on the Ant Colony Optimization (ACO) algorithm, a test scheduling to reduce the test application time under the peak power constraint as well as the constraint of maximum TAM bus width. Experimental results show that the algorithm is more effective in reducing test time than the earlier published methods.