Cu-Ni-P alloys with different atomic ratios of Ni:P (2:1, 3:1, 4:1 and 5:1) were designed, and the microstructure characteristics and phase extraction treatments of ingots and melt-spun ribbons were discussed. Results show that Cu-xNi-4.5P ingots are composed of Cu and multiple Ni-P phases, including Ni₅P₄, Ni₁₂P₅ and Ni₃P. With melt-spun process, the phosphides mainly exist in the form of Ni₁₂P₅ and Ni₃P compounds. Meanwhile, further increasing nickel concentration of alloys can cause the structure-coarsening of phosphides in some degree. By controlling the solidification behavior and phase extraction process, Ni-P particles with multistage pore structure can be obtained, in which the pores are formed due to the etching of Cu dendrites and Cu existing in eutectic structure and solid solution region. Thus, phase extraction from metallic alloys provides a new controllable method to synthesize functional multistage porous phosphides.