Abstract: Abstract: Crop straw is an important biomass resource. The comprehensive utilization of crop straw not only protects the environment of producing areas and increases the farmers' income, but also lays foundation for circular economy and emerging industry. The main utilization approaches for crop straw are converting to animal feed, fertilizer, fuel, material of edible fungi, and material of industry. In order to optimize the utilization approaches of crop straw, the evaluation indices are assigned based on information from references, which are measured by nine grade assignment. The evaluation indices are formed by functional indices, economical beneficial indices, environment beneficial indices and adaptability indices. The functional indices are formed by maturity of engineering and effective transformation of engineering. The economical beneficial indices are formed by the utilization cost of crop straw per ton and the benefit of resource substitution per ton. The indices of environmental benefit are formed by the profit of waste reduction per ton and the secondary pollution degree per ton. The adaptability indices are formed by the coordination degree of regional crop straw variety, the coordination degree of regional crop straw density, the coordination degree of regional crop straw collection, transportation, storage and the coordination degree of regional policy planning. The combination weights method based on entropy and rank correlation analysis method is used to obtain the weights of evaluation index, and GC-TOPSIS (technique for order preference by similarity to ideal solution combined by grey correlation) serves as decision-making method. The combination weighting method gives consideration for both subjective and objective influencing factors, by comparing with simple subjective weighting method or objective weighting method, which is scientific, easy, and feasible. GC-TOPSIS method is a new kind of relative similarity degree by combining the Euclidean distance with grey correlation degree. It reflects the distances and the different shapes among a selected scheme, the ideal solution and negative ideal solution. The implication is clearer, valid and feasible. And these methods are applied to the optimization of utilization approaches of crop straw in Heilongjiang province. The preference order of five utilization approaches obtained for Heilongjiang province in this paper is: as feed > as fertilizer > as fuel > as material of edible fungi > as material of industry, which is consistent with actual development and scheme in Heilongjiang province. At the same time, the optimization method provides foundation to scheme the various choices of utilization approaches in Heilongjiang province. Furthermore, the evaluation indices are assigned by information from the reference, which is practicable and gives access to optimized choices.