Abstract: The present application relates to a self-sustained release immune adjuvant suspension comprising microparticles composed of a lipid soluble immune adjuvant and a surfactant, the balance being a dispersant, wherein the lipid soluble immune adjuvant is coated with the surfactant to form the microparticles which are dispersed in the dispersant to form a suspension. The self-sustained release immune adjuvant suspension can be retained in a tumor for a long time and can maintain a sustained release property, and can also inhibit the growth of distal metastatic tumors and reduce the probability of tumor recurrence by means of an immune response. The present application further provides a preparation method for a self-sustained release immune adjuvant suspension, and use of the self-sustained release immune adjuvant suspension in a sensitizing formulation used for tumor therapies, such as, radiotherapy, chemotherapy, or thermotherapy.