The ordered decomposition of problems is defined formally. And the conductive rate and the conductive branching factor are proposed to measure the interaction between subgoals, which provide a quantitative criterion for setting subgoals in practice. Furthermore, it is shown how to construct the transfer-station network, which is a kind of ordered decomposition in the structure of networks, and has more potentialities in application to problem solving to improve the system efficiency. Finally, an algorithm using this network,called Tw,is presented.