<p>Electric-field control of magnetic order is of significant physical interest and holds great potential for spintronic applications. However, it has rarely been reported in two-dimensional (2D) van der Waals (vdW) magnets, primarily due to the inherently weak coupling between spin order and electric fields. Here we propose a general spin-electric potential mechanism that significantly enhances the magnetoelectric coupling. The spin-electric potential refers to the spin-order-dependent electric dipole potential energy originating from the polar spin interactions in asymmetric magnetic systems. Due to the additional spin-electric potential, the relative stability of different interlayer spin orders in a vdW heterobilayer can be significantly manipulated by external electric fields. Based on this mechanism, we design a series of 2D vdW all-magnetic heterobilayers, such as CrI₃/MnSe₂, in which a transition from interlayer spin-parallel (SP) to spin-antiparallel (SAP) order is realized by a feasible electric field of around 0.1 V/Å. Our findings not only reveal a novel magnetoelectric coupling mechanism, but also present a practical strategy for achieving pure electric field switching of magnetic order.</p>