•It was found for the first time that soybean oil rich in ω-6 polyunsaturated fatty acids (>50%) emerged as an important risk factor for bladder cancer in northeast China.•No such clinical trial had been carried out in northeast China which owned their specific eating habits.•Intake of nuts and marine fish was inversely related to bladder cancer.•Intake of milk and dairy products was inversely related to bladder cancer in male patients. The aim of this study was to explore the association between dietary fatty foods and the risk for bladder cancer. Patients newly diagnosed with bladder cancer (n = 113) and 292 controls were recruited. A food frequency questionnaire (FFQ) was used to investigate the food intake within 1 y. Multivariate logistic regression model was used to estimated odds ratio (OR) between different types of fatty food consumption and bladder cancer. The consumption of soybean oil, the largest proportion of cooking oil, in both groups were much higher than the Chinese recommended dietary intake, especially in the control group. Higher intake of red meat was also observed in bladder cancer cases, although lower intakes of marine fish, egg, milk, and dairy products and nuts were observed in controls. After adjusting for potential confounders, the intakes of marine fish and milk and dairy products were negatively correlated with bladder cancer, with the adjusted OR of 0.28 (95% confidence interval CI, 0.15–0.55) and 0.36 (95% CI, 0.19–0.69). Total nuts were related to a 76% reduction in bladder cancer risk (OR, 0.24; 95% CI, 0.12–0.48). There was clear and positive association between soybean oil and bladder cancer risk with OR of 3.47 (95 % CI, 1.69–7.14). In stratified analyses by sex and smoking status, the relationship was similar for most results, except for milk and dairy products. The negative correlation between milk and dairy products and bladder cancer risk was only found in men; and milk and dairy products and bladder cancer risk were irrelevant by smoking status. No significant association was found between the intakes of other foods and bladder cancer risk. Intake of nuts and marine fish may be beneficial for the prevention of bladder cancer. The protective effect of milk and dairy products was only found in men with bladder cancer. High soybean oil intake was a risk factor for bladder cancer.