To identify and test the quality of commercial goat milk powder sold in different areas, reversed-phase high performance liquid chromatography (RP-HPLC) was used to determine the protein composition of 35 samples of pure and formulated goat milk powder purchased in different regions (Shaanxi and non-Shaanxi) of China and in other countries, and the difference in protein composition among goat milk powder from different production areas and that between pure and formulated goat milk powder were analyzed. The results showed that the contents of αs2-casein and β-casein in formulated milk powder were 20% and 24% lower than those in pure milk powder, respectively, and the contents of κ-casein and whey proteins were 30% and 50% higher than those in pure milk powder, respectively. However, the protein composition and content of pure goat milk powder from different regions were similar. Therefore, RP-HPLC is useful for protein quality evaluation of commercial goat milk powder.