This invention discloses an adenine-based heat stabilizer and its application in PVC composites, belonging to the field of heat stabilizer technology. The heat stabilizer is an adenine-based substance or a compound of an adenine-based substance and an auxiliary stabilizer. The adenine-based substance is adenine or
adenine nucleoside, and the auxiliary stabilizer is at least one of
calcium salt stabilizers,
zinc salt stabilizers, and
polyol stabilizers. This adenine-based heat stabilizer can improve the initial whiteness of PVC and impart better long-term stability to PVC. Its application in PVC composites can effectively improve the
thermal stability and mechanical properties of PVC composites, possessing practical application value.