Non-alcoholic fatty liver disease (NAFLD) is an important health issue worldwide. We aimed to develop a simple model to determine the presence of NAFLD in a Chinese population. A cross-sectional study with 9602 subjects was conducted. Potential predictors were entered into a stepwise logistic regression analysis to obtain the model. We used 148 patients with liver biopsy to validate this model. The model, named the ZJU index, was developed based on body mass index (BMI), fasting plasma glucose (FPG), triglycerides (TG), and the serum alanine aminotransferase (ALT) to serum aspartate transaminase (AST) ratio. The area under the receiver operating characteristic curve (AUROC) of the ZJU index to detect NAFLD was 0.822. At a value of <32.0, the ZJU index could rule out NAFLD with a sensitivity of 92.2%, and at a value of >38.0, the ZJU index could detect NAFLD with a specificity of 93.4%. In patients with liver biopsy, the ZJU index could detect steatosis with good accuracy, with an AUROC of 0.896. This study revealed that the ZJU index is a helpful model to detect NAFLD for community physicians in China. It was validated not only by a validation cohort but also by pathological data.