The invention relates to a low-permeability reservoir comprehensive geological-engineering classification evaluation method. The method comprises the steps that reservoir geological classification evaluation indexes are constructed, specifically, a gray correlation method is used for obtaining reservoir geological main control factors, influencing the fracturing effect, of a low-permeability reservoir; based on the reservoir geological main control factors, low-permeability reservoir geological classification evaluation indexes are constructed by using a principal component analysis method; reservoir engineering classification evaluation indexes are constructed, specifically, geomechanical main control factors, influencing the fracturing effect, of the low-permeability reservoir are obtained by using a grey correlation method; based on the geomechanical main control factors, low-permeability reservoir engineering classification evaluation indexes are constructed by using an analytic hierarchy process; and according to the classification threshold values of the reservoir geological classification evaluation indexes and the reservoir engineering classification evaluation indexes, reservoir categories are divided. According to the method, comprehensive evaluation is carried out from two aspects of geology and engineering, the fracturing effect of the low-permeability reservoir canbe prejudged and evaluated more scientifically and reasonably, and a more scientific and accurate basis is provided for fracturing well selection and fracturing construction parameter selection.