Colorectal cancer (CRC) is one of the most common malignant tumors worldwide, and its incidence has been increasing in recent years, especially among young adults. Non-genetic factors, such as dietary habits, lifestyle and intestinal flora, play an important role in the development of CRC. Dietary factors have a close relationship with CRC development. Insufficient fiber intake and excessive consumption of red and processed meat are generally considered major high-risk factors for CRC, while vegetables and fruits are considered as beneficial factors. The roles of calcium supplements, vitamin D, dairy products, and different dietary patterns in the development of CRC are still controversial. Furthermore, obesity, smoking, alcohol consumption, and lack of physical exercise are also associated with the risk of CRC. The imbalance of intestinal flora is also believed to be associated with the development of CRC. Optimizing dietary habits and maintaining a healthy lifestyle can significantly reduce the risk of CRC. Non-steroidal anti-inflammatory drugs and estrogen supplementation may have beneficial effects in reducing the risk of CRC. For certain individuals at high risk, pharmacological intervention may serve as an effective preventive measure.