The invention provides a novel synthetic method of Palbociclib, comprising the following steps: 1) under the action of alkali and a solvent, an intermediate V and an intermediate B1 undergo a condensation reaction to obtain a compound VI; 2) the compound VI undergoes exchange with a Grignard reagent, and then the exchange reaction product reacts with an acylation reagent to obtain a compound VII; when X is acetyl, the compound VI is the compound VII; 3) the compound VII undergoes deprotection reaction under the action of hydroxyethanesulphonic acid and finally salification is conducted so as to obtain the finished product Palbociclib X. the synthetic method has a simple process route, is low-cost, and is suitable for industrial production. The synthetic route is as shown in the specification.