Abstract: Provided are a class of compounds, a stereoisomer, an optical isomer, a pharmaceutically acceptable salt, a prodrug, a solvate (for example, a hydrate) or an isotope derivative thereof. The compounds have a tri-heterocyclic structure (for example, the structure represented by formula (A)), which is a novel structure, thereby providing a new direction for the development of SOS1 inhibitor drugs. In-vitro enzyme activity inhibition activity studies show that the compounds have a relatively strong inhibition effect on SOS1 and can be used as a prospective compound for preventing and/or treating SOS1-mediated diseases. Moreover, said compounds also exhibit significant inhibitory activity on NCI-H358 cell proliferation. Furthermore, a specific synthesis method is provided. The synthesis method is simple in process, convenient to operate and beneficial to large-scale industrial production and use.