Parallel Test is a main direction for the next generation Automatic Test System. The key factors that influence the parallel test system's resource configuration are analyzed based on the essence conception of Parallel Test. Then the means of resolving the complex problem of the parallel test is given. The signal model of unit under parallel test and the interface model of the test resource are studied. In order to reduce the parallel test system cost and improve the system efficiency, the conception of parallel test optimized task list is put forward. The method of parallel test system's resource configuration is presented based on the conception.