The three-dimensional layered compound MAX phase has excellent mechanical property of both metals and ceramics, which is generally considered as a kind of high safety structural materials. In recent reports, V₂(Sn, A)C (A = Fe, Co, Ni and Mn) materials showed that antiferromagnetic property can be obtained by inserting the subgroup elements into A layer of MAX phase by molten salt method. However, how to further regulate magnetic properties of MAX phase through design of its crystal structure has attracted the attention of scholars in the field of spintronics and other fields. In this work, four new MAX phases of (V, Nb)₂(Sn, A)C (A = Fe, Co, Ni and Mn) were synthesized based on M/A double solid solution by molten salt method, and proved to be synthesized successfully. Magnetic property of the MAX phases was checked by SQUID (superconducting quantum interference device magnetometer). It is found that the change of Curie temperature is correlated with tetragonal ratio (c/a) and elemental composition. Changes of lattice parameters, tetragonal rate and magnetic results before and after introducing Nb element into M site were further compared. Besides, the H_c and M_r of (V, Nb)₂(Sn, Fe)C, (V, Nb)₂(Sn, Ni)C, and (V, Nb)₂(Sn, Mn)C decreased and the M_r increased compared with V₂(Sn, A)C (A = Fe, Ni, Mn) before introducing Nb element into M site. All these results were opposite after introducing Nb element into M site of V₂(Sn, Co)C which reveals the influence of M/A-site doble solid solution to the magnetic property of MAX phase, and provides a new way for tailoring magnetic property of MAX phase.