Daniudi Gasfield is characterized by multi-layers in vertical, large interval between layers, tight reservoir and low deliverability of single layer, even no natural deliverability without fracturing. The grey correlation analysis method is used to optimize the factors which affect the well selection in fracturing. The level analysis principle of system engineering which takes the complexity and malconformation of each factor into consideration is applied to ascertain the weight of each factor. The application result proves the scientificity and applicability of this grey correlation analysis method.