Abstract: Metabolic flux analysis of cellular growth is very important for the fe rmentation processes which have a small yield of metabolic products. In this paper, a new analysis method is developed to calculate the least square solution of the intercellular metabolic flux distribution, which successfully combines cellular elemental composition data with cellu lar molecular composition data by incorporating carbon balance and generalized d egree of reduction balance into the calculating process. This method can make th e result more reliable, because it utilizes more measurement data and ensures data consistency. It should be mentioned that all results are derived from a simpl ified metabolic network of B.subtilis , which is created by representing the complex biomass synthesis network with some precursor requirement rates.