This paper proposes a binary ant system(BAS),an improved hyper cubeframework of ant colony optimization(ACO) applied to multidimensional knapsack problem(MKP).Different to other Ant Systems applied to MKP,BAS designs a specialpheromone laying method based on the binary solution structure,admits infeasible solution during the solution construction procedure,and uses a problem specifc repairing operator to repair those infeasible solutions generated in each iteration.BAS uses aspecial pheromone up...