Abstract: Project option assessment has been well solved by using fuzzy decision method.Fuzzy decision model considering economic benefit and stability was established aiming to solve the question about stability of open pit slope and underground stope during the transition period from open pit to underground mining,in which fuzzy mathematics was used and stress and strain of the slope and underground stope caused by digging the first section combined with economic indices of ore block stripping ratio and recovery rate were comprehensively considered.By means of scientifically determining the membership function of each factor and establishing the weight of each factor by constructing the judging matrix through binary taxis,the optimal one was selected from nine schemes made up of different combination of room structural parameters,which could ensure not only safety production but also better economic profit.