A kind of relative reduction algorithm based on hybrid genetic algorithm was proposed. Genetic Algorithm combining with Simulated Annealing produces HGA in order to improve performance of GA. And the HGA is utilized to search of minimum condition attributes and their values. The algorithm is introduced into construction management so some decision rules can be extracted. Construction managers ensure to finish expected task in provided period according to the decision rules. The whole construction process will be managed by brainpower if every activity has its own decision rules.