The kidney is the body’s most important organ and the protein components in urine could be detected for diagnosing certain diseases. The amount of IgG protein in urine could be used to determine the degree of kidney function damage. IgG protein in human urine was detected by vertical flow paper-based microfluidic chip, double-antibody sandwich immunoreaction, and cell phone image processing. The results showed that using an IgG antibody concentration of 500 μg/mL and a gold standard antibody concentration of 100 μg/mL, the image signal showed a good linear relationship in the range of IgG concentration of 0.2-3.2 μg/mL, with R²=0.973 3 achieved. A complete set of detection devices were designed and the detection method showed good non-specificity.