The invention discloses a GIS (Geographic Information System) based nonparametric river network concentration model and belongs to the technical field of watershed concentration models. According to the model, a relational expression of the sectional river width and the mean river width is obtained through watershed outlets subjected to statistics during parameter quantization; in combination with a GIS technology with high development speed in recent years, a nonparametric computing model for river network concentration is realized and the number of parameters in concentration computing is reduced; rating parameters are definite, so that the indefiniteness caused by influence of the rating parameters is avoided; and the model is high in applicability and comprehensive in universality, so that the model can be comprehensively popularized.