The present invention provides a thienopyrimidinone derivative, a preparation method thereof, and an application thereof in manufacturing of antitumor drugs. The derivative has a structure as represented by general formula (I), comprising a single stereoisomer or racemic mixture thereof, wherein R is independently selected from hydrogen (H) or deuterium (D); R 1 and R 2 independently, at each occurrence, represent H, D, F, Cl, I, cyano group (CN), or N 3 , and when R represents H, R 1 and R 2 do not synchronously represent H; R 3 , R 4 and R 5 independently, at each occurrence, represent an alkyl group, a cycloalkyl group, a heterocyclic group, an aromatic ring group, or a heteroaryl ring group, which are substituted or unsubstituted.