A strong Fermi level pinning (FLP) effect can induce a large Schottky barrier in metal/semiconductor contacts; reducing the Schottky barrier height (SBH) to form an Ohmic contact (OhC) is a critical problem in designing high-performance electronic devices. Herein, we report the interfacial electronic features and efficient modulation of the Schottky contact (ShC) to OhC for MoSi2N4/M3C2 (M = Zn, Cd, Hg) van der Waals heterostructures (vdWHs). We find that the MoSi2N4/M3C2 vdWHs can form a p-type ShC with small SBH with the calculated pinning factor S ≈ 0.8 for MoSi2N4/M3C2 contacts. These results indicate that the FLP effect can be effectively suppressed in MoSi2N4 contact with M3C2. Moreover, the interfacial properties and SBH of MoSi2N4/Zn3C2 vdWHs can be effectively modulated by a perpendicular electric field and biaxial strain. In particular, an efficient OhC can be achieved in MoSi2N4/Zn3C2 vdWHs by applying a positive electric field of 0.5 V/Å and strain of ±8%.