Abstract: To cope with the problem of test wrapper/T AM co-optimization of SoC,this paper proposes an ant colony algorithm as an optimization scheme．The research work includes two steps． Firstly,an ant colony optimization （ACO） algorithm for IP test wrapper is designed to shorten the length of the longest scan chain in the SoC chip and decrease the test time for single IPs．Based on the look up table acquired from the first step, ACO algorithm is applied in test wrapper/T AM co-optimization problem to decrease the test time for the entire SoC chip by approximating to the optimal result on test bus division．Experimental results on ITC'02 benchmark circuits proved the effectiveness of the scheme．