Abstract: Traditional statistical analysis method is chaotic in scatters and huge in data bulk and can hardly analyze and summarize the laws, so it fails to accurately determine the main factors controlling the stimulated reservoir volume (SRV) of tight oil by horizontal well. A method for evaluating the effect of horizontal well SRV was proposed on the basis of fuzzy set theory. Firstly, a horizontal-well production classification method was developed according to the fuzzy set theory, and 55 tight-oil horizontal wells in the Ordos basin were classified based on the production. Then, the slope of the change interval of each factor was obtained by normalizing the classified data, and accordingly the storm chart of production influence factor was plotted. Finally, based on the weight of each influence factor, the production prediction model of horizontal well SRV including multiple factors was established by means of multiple regression method. It is indicated that this new method can reflect the effect of each factor on the development result of horizontal well SRV clearly and accurately, and provide the influential degree of each factor on the production of horizontal well SRV. What’s more, analysis was conducted on the actual case of oilfield production, and the average relative error of predicted production is only 7.6%. The research results provide the theoretical basis for the optimization of fracturing scheme and the prediction of production in the field.