2D material with superior transport property are widely used for material improvement and modification. Among them, metal selenide holds merits of large interlayer and favorable conductivity. Possessing bigger radius of selenium and weaker M−Se bond, the conversion reaction can be more efficient compared to metal oxides and sulfides. Here, amorphous MoP@MoSe/SnPO hierarchical nanofibers was prepared through electrospinning with Se addition and its ratio adjustment during thermal treatment, the composition and surface morphology were modulated accordingly. Surprisingly, the introduction of Se can alter the distribution of Sn, and induce the formation of SnPO. The corresponding formation mechanism was explored via ratio and thermal treatment control. As a result, consisting of inner amorphous MoP skeleton and external conductive MoSe/SnPO layer, the material performance got greatly improved by the core–shell structure.