Abstract: A thienopyrimidine compound (a compound of formula N) and a preparation method therefor are provided. Specifically, the preparation method includes the steps of: (a) in a solvent A, reacting, in the presence of an organic base and acyl chloride, a compound of formula N-2 with 3-amino-6-methoxypyridazine to obtain a compound of formula N-1; and (b) in a solvent B, converting, in the presence of a base, the compound of formula N-1 into the compound of formula N. The preparation method does not require toxic and expensive reagents, has mild reaction conditions and a high product purity, and is suitable for industrial production.