Perpendicular magnetic anisotropy (PMA) is one of the most significant technologies to be used in next generation spintronic devices due to its potential for promoting thermal stability and device miniaturization. It is an important issue to find an efficient way to modulate its property in the process of PMA application. In this work, we report the phase-transition controlled magnetic anisotropy modulation in the VO2/(Co/Pt)2 heterostructure, where VO2 is introduced into the system to apply an interfacial strain by its metal-insulator transition. A large reversible modulation of PMA reaching 3 × 105 erg/cm3 is observed during this process. The calculated energy density variation of interfacial anisotropy reaches 0.85 erg/cm2, which shows a significant advantage over traditional modulation strategies. Further experimental results including magnetization change versus temperature, strain buffered modulation, and pre-strained sample comparison prove that the interfacial coupling between VO2 and PMA layers plays a crucial role in this modulation. This work, demonstrating great potential for phase-transition materials in efficient magnetic anisotropy modulation, would benefit the exploration of low-power consumption devices.