The invention discloses a compound isosorbide mononitrate sustained release tablet and a preparation method thereof and belongs to the technical field of sustained release preparations. The preparation method comprises 1, carrying out boiling granulation on isosorbide mononitrate and a sustained release material to obtain skeleton sustained release particles, adding auxiliary materials into the skeleton sustained release particles, carrying out screening and finishing on the skeleton sustained release particles and the auxiliary materials and carrying out uniform mixing, 2, uniformly blending aspirin and pharmaceutic adjuvants, preparing fast release particles through a dry rolling granulator, adding a lubricant into the particles, carrying out screening and finishing on the fast release particles and the lubricant and carrying out uniform mixing, 3, pressing the mixtures from the step 1 and the step 2 through a double-layer tablet machine to obtain a tablet with a sustained-release layer and a fast-release layer, and 4, coating the tablet obtained through the step 3 with a moistureproof coating material (opadry-AMB) so that a film-coated tablet is obtained. The preparation method utilizes a skeleton sustained release technology and a fast release preparation technology to control a drug release rate so that bioavailability is improved.