Objective To evaluate the clinical value of magnifying chromoscopy in combination with Kudo criteria in detection and diagnosis of colorectal lesions. Methods After conventional electronic colonoscopic diagnosis of 125 colorectal lesions, staining and magnifying observation by chromoscopy were made with Kudo criteria, and biopsy specimen and resected samples were sent for pathologic examinations. Results The accuracy of ordinary colonoscopy and magnifying colonoscopy compared with histological diagnosis of inflammatory polyps, tubular adenomas, villous adenomas and colorectal cancer was 95.62%, 80%, 90% and 100% respectively and 100%, 93.75%, 92.86% and 100% respectively. The overall accuracy of two procedures was 85.6% and 95.2% respectively. Conclusions Magnifying chromoscopy is valuable in detection of tiny and slightly elevated colorectal lesion, and has high efficacy in judging the nature of lesions with Kudo criteria.