The invention relates to a preparation method of acylated collagen. The preparation method comprises a step of preparing a de-telopeptide collagen
salting-out substance and a step of acylating the de-telopeptide collagen
salting-out substance, wherein the step of preparing the telopeptide-removed collagen
salting-out substance comprises the following steps: soaking bovine
achilles tendon in a
hydrogen peroxide solution, and cleaning with water; soaking with a triton X-114 solution, continuously soaking with a
sodium hydroxide solution, washing with water until the solution is neutral, squeezing to remove water, and freezing, irradiating and sterilizing; the method comprises the following steps: swelling sterilized bovine
achilles tendon powder with a
citric acid solution, dispersing and crushing, and performing acid enzymatic extraction with an
acetic acid solution and pepsase; filtering the obtained enzymatic
hydrolysate, centrifugally collecting upper-layer clear and transparent liquid, and
salting out by using a saturated
saline solution; adding the obtained primary salting-out substance of the telopeptide-removed collagen into an
acetic acid solution, collecting upper-layer clear and transparent liquid, and salting-out by using a saturated
saline solution to prepare a secondary salting-out substance of the telopeptide-removed collagen. The acylated collagen prepared by the method is low in endotoxin.