Based on first-principles calculations, we systematically study the stacking energy and interlayer magnetic interaction of the heterobilayer composed of CrI 3 and CrSe 2 monolayers. It is found that the stacking order plays a crucial role in the interlayer magnetic coupling. Among all possible stacking structures, the AA-stacking is the most stable heterostructure, exhibiting interlayer antiferromagnetic interactions. Interestingly, the interlayer magnetic interaction can be effectively tuned by biaxial strain. A 4.3% compressive strain would result in a ferromagnetic interlayer interaction in all stacking orders. These results reveal the magnetic properties of CrI 3 /CrSe 2 heterostructure, which is expected to be applied to spintronic devices.