Abstract: Proteinuria is one of the common symptoms of kidney disease in children. At present, there is neither unanimous understanding of the classification of proteinuria, nor clear thoughts of diagnosis of proteinuria in pediatrics. This paper summarizes and organizes the classification and diagnosis of proteinuria, and proposes the concept of proteinuria in a broad and narrow sense, as well as the four-step diagnosis idea of qualitative, quantitative, location， and cause determination. It especially points out that the ratio of α 1 microglobulin to microalbumin close to or greater than 1 in urine can be used as the judgment standard for the location diagnosis of proteinuria in small molecule proteinuria.

Key words: proteinuria;　diagnosis approach;　child