Abstract: The technology of colorful reeling cocoon silk is being three difficult problems in which people add pigment to the silkworm food. The first is how to raise colorific deepness and purity. The second is raise the fastness of a color. The third is how to enrich color species of colorful cocoon silk. This three problems were studied and discussed in this paper. People using add pigment to the silkworm for colorful cocoon. The result indicated colorific deepness, purity and fastness of a color have many affiliations with pigment, species of silkworm, method of add food and circumstance. Availability ingredient of pigment and concentration of pigment is its decisive impact.