Colorectal tumor is one of the most common malignant tumors in our country and seriously endangers our national health. It is an effective strategy to reduce the harm of colorectal tumors by screening the target population with simple and effective detection methods and early diagnosis. However, although great progress has been made in colorectal cancer screening in China, there are still some problems such as insufficient sensitivity and specificity of screening methods, poor acceptance and compliance, which affect the screening effect. As an emerging detection technology in recent years, liquid biopsy has rich connotations, multiple detection targets to choose from, and advantages such as convenient sampling, less trauma, high population acceptance, and easy promotion and development. It has broad application prospects in the early diagnosis of colorectal tumor screening. Blood ctDNA can provide panoramic data of tumors in patients, which is relatively high in patients with early stage tumors, and is an important target for early colorectal cancer diagnosis and screening.