The penalty parameter of penalty function method is systematically analyzed and discussed. For the problem that Deb’s feasibility-based rule doesnot give the detailed instruction as how to rank two solutions when they have the same constraint violation, an improved Deb’s feasibility-based rule is presented, which can be seen as a reference standard. And based on this, the upper and lower boundary of penalty parameter that affects the ranking is obtained. The example verifies the
effectiveness of the systematical analysis, which provides a basis for the future algorithm design based on the penalty parameters.