Abstract: The sequencing optimal decision of parallel activities is one of the most effective and familiar methods in the issue of resource-constrained schedule planning.Researches on this problem have focused on the indivisible activities mainly ever before.In fact,many activities can be decomposed into arbitrary portions.In this case,this paper proposed the minimum project duration theory and on the foundationes-tablished the tardiness model of sequencing the two divisible parallel activities,then gave the theoretic proof.Furthermore,the problem of sequencing an activity selected amongn divisible parallel activities with a designated acivity is also studied in this paper.Based on the tardiness model,the optimal method and theoretic proof are provided.Especially for a large scale network,the superiority becomes very distinct.

Key words: project management, sequencing optimal decision of activities, divisible activities, tardiness