Objective: To investigate the levels of urinary exosomal miR-194-5p in children with idiopathic nephrotic syndrome (INS) and its clinical value as a non-invasive auxiliary diagnostic marker. Methods: Urine samples were collected from 101 INS children and 98 sex- and age-matched healthy children, and the levels of urinary exosomal miR-194-5p were determined by quantitative real-time polymerase chain reaction (qRT-PCR). The clinical value of urinary exosomal miR-194-5p in the diagnosis of children′s INS was evaluated by the ROC curve and correlation analysis. Results: The levels of urinary exosomal miR-194-5p in INS children (2.420 [0.650,9.515] fmol/L) were significantly higher than that in healthy controls (0.360 [0.220,0.653] fmol/L, U=1 552, P＜0.01). Compared with the INS children before treatment, the levels of urinary exosomal miR-194-5p in clinical remission period decreased significantly (0.320 [0.145,0.523] fmol/L vs 0.975 [0.375,4.358] fmol/L, W=708, P＜0.01). Moreover, the levels of miR-194-5p in INS children with heavy urine protein (8.430 [7.225,13.070] fmol/L) were significantly higher than that with light urine protein (2.130 [1.180,3.090] fmol/L, U=0, P＜0.01). The area under the ROC curve (AUC ROC ) of miR-194-5p was 0.843 (95%CI: 0.789-0.897) for the diagnosis of INS children. Spearman correlation analysis showed that the levels of urinary exosomal miR-194-5p in INS children were negatively correlated with serum albumin levels (r=-0.300), and were positively correlated with serum total cholesterol levels (r=0.278) and 24-hour urine protein content (r=0.296, all P＜0.01). Conclusion The levels of urinary exosomal miR-194-5p in INS children increase obviously, and are closely associated with 24-hour urine protein, serum albumin and total cholesterol levels, indicating that urinary exosomal miR-194-5p may be serve as a new non-invasive fluid biopsy molecular marker for the auxiliary diagnosis of INS in children.