The electromagnetic and electronic properties of six atomic terminations CrCr-ScFe-T, ZrSb-ScSn-T, CrCr-ScSn-B, ZrSb-ScFe-B, CrCr-ScFe-V, and ZrSb-ScSn-V in complete Heusler alloy Cr2ZrSb/Sc2FeSn(100) heterojunction were systematically studied by first-principles calculation based on density functional theory. The results show that the interactions between the interface atoms causes the unevenness of the interface atomic layer, which leads to the increase of the mechanical mismatch rate of the interface layer. Compared with the high spin polarization in the bulk, the spin polarization of the heterojunction is destroyed to varying degrees. Fortunately, the termination ZrSb-ScFe-B retains a high spin polarization value and has a tunnel magnetoresistance of 429.29% at low temperature according to the Julliere model, indicating its potential application prospects in spintronic devices