To analyze the risk factors of laparoscopic colorectal surgery conversion rate, and establish the scoring system, retrospective study was performed and 429 patients who underwent laparoscopic colorectal surgery were analyzed. Conversion rate was 15.58%, and the risk factors include age, body mass index (BMI), operation number, abdominal operation history, invasion or metastasis, and tumor size. Scoring system established with age (≥ 65: 7, <65: 0), weight (BMI ≥ 25: 11, BMI <25: 0), operation number ≤ 25 (yes: 5, no: 0), abdominal operation history (yes: 12, no: 0), tumor size (≥ 6 cm: 22<6 cm: 0), and invasion or metastasis (yes: 34, no: 0). 18.5 uses to predict the conversion. Conversion rate below 18.5 is 5.21%, and above 18.5 is 42.62%. We concluded that scoring system is simple, convenient, and applicable.