Abstract: Disassembling the organizing process of enterprises alliance and enterprises group into four stages and establishing mathematical model of the organizing costs. The model of organizing cost for enterprises alliance and enterprises group in crisp case are given first in terms of references, then extending the model of organizing cost to the fuzzy sense suitable for practical case, which is fuzzified model's coefficients of terms related to time, the solution is attained by using fuzzy optimization technique and nonlinear dynamic programming to allocate time distribution of different organizing stages. The proposed method provides effective theoretic reference for enterprises to choose development strategies according to different practical situations.