The present invention discloses a semi-aromatic polyester, a preparation method therefor and use thereof. The content of hydroxyl in a semi-aromatic polyester is controlled, and particularly, the content of hydroxyl linked to aliphatic dicarboxylic acid in the semi-aromatic polyester is controlled to 17-40 mmol/kg, the content of hydroxyl linked to aromatic dicarboxylic acid in the semi-aromatic polyester is controlled to 17-40 mmol/kg, and the total content of hydroxyl is controlled to 35-80 mmol/kg, such that the compatibility of the semi-aromatic polyester with materials, e.g., polylactic acid can be significantly improved, thereby obtaining a high-strength tear-resistant film material.