The invention relates to a manufacturing process of soluble chitin. The manufacturing process comprises the following steps: (1) preparing shrimp shells or crab shells, cleaning the shells with water,and drying the shells; (2) immersing the cleaned shrimp shells or crab shells in diluted hydrochloric acid at a concentration of 6 to 8 percent, and uniformly stirring the shells and the diluted hydrochloric acid; (3) putting the shrimp shells or crab shells subjected to acid treatment into a pot, adding clean water and sodium hydroxide at a concentration of 8 to 10 percent, and boiling the mixture; (4) adding water into the shrimp shells or crab shells subjected to acid and alkali treatment, then adding the shells into a potassium permanganate solution, removing pigment, and cleaning the shells with water; (5) pressing the discolored shrimp shells or crab shells to remove water, and spreading the shrimp shells or crab shells for drying to obtain insoluble chitin; (6) putting the insoluble chitin into a jacketed pan, adding a caustic soda solution at a concentration of 40 percent, carrying out uniform stirring, and maintaining temperature at 60 to 65 DEG C for 24 hours. The manufacturing process has the beneficial effects that the extraction process is simple, the chitin extraction rate is high, and the extracted chitin is high in purity and high in brightness.