Abstract： This paper introduces Professor DING Jiyuan's clinical experience in treating colorectal cancer with insect medicines based on the theory of phlegm，blood stasis，toxin blended in the collaterals. Professor DING Jiyuan believes that the occurrence and development of colorectal cancer are rooted in the fundamental pathogenesis of deficiency of spleen and stomach as well as internal deficiency of healthy qi， with the core pathogenesis of the intermingling and stagnation of phlegm，blood stasis，and toxin in the intestinal collaterals，resulting in a syndrome of deficiency in root and excess in branch and deficiency interwoven with excess. Among these，phlegm and blood stasis are not merely pathological products but are lingering pathogenic factors that are blended with cancer toxin and become deeply hidden in the intestinal collaterals； collateral-vessel obstruction then becomes the key to the stagnation of phlegm，blood stasis，and toxin. On the basis of strengthening healthy qi and consolidating the root，Professor DING Jiyuan employs insect medicines as the core agents for unblocking the intestinal collaterals and dispelling long-standing stagnation of pathogenic factors. Leveraging their properties of resolving phlegm，dispelling stasis，removing toxicity， and unblocking collaterals，he flexibly modifies the insect medicines according to various pathological stages of phlegm， blood stasis，toxin blended in the collaterals，establishing a hierarchical application of insect medicines that synergizes with Chinese herbal medicines. Clinically， this approach significantly improves symptoms and prolongs survival in patients with colorectal cancer.