Provided in the present application are benzo[d]isoxazole compounds, a preparation method therefor and an application thereof. The benzo[d]isoxazole compounds are a group of compounds having novel structures and which act as bromodomain and extra-terminal domain (BET) bromodomain receptor inhibitors. The group of compounds may effectively inhibit the bromodomain of BET family proteins, thereby blocking the interaction between BET family proteins and chromatin histones, thus regulating gene transcription, causing changes in downstream signal paths, and having a significant impact on many diseases. The present invention is effective in the treatment of tumors, and may also improve the treatment of other diseases, thus having broad application prospects.