The invention discloses a sweet spot identification and comprehensive evaluation method for a tight sand reservoir. According to the method, eight conventional logging curve data are taken as a basis. By utilizing the SPSS data analysis software, common factors capable of comprehensively reflecting the characteristics of a reservoir in a target area are extracted based on the PCA (principal component analysis) method. According to the physical significance of each common factor, the sweet spots of the tight sand reservoir are recognized, and a sweet spot qualitative recognition model for the tight sand reservoir is established. On the above basis, a common factor calculation model for porosity and permeability is established in conjunction with physical property test data, so that the types of the reservoir are divided. According to the physical property parameters of various reservoir types and the parameter characteristics of common factors, a quantitative evaluation standard for the tight sand reservoir is determined. Therefore, the qualitative recognition and the quantitative evaluation for the sweet spots of the tight sand reservoir are realized. Based on the method, a novel idea and a novel method are provided for the interpretation and evaluation of the tight sand reservoir. Therefore, the interpretation and evaluation reliability of the tight sand reservoir is improved. The exploration and development cost is reduced.