The invention discloses a multi-station linkage rating curve fitting method, and the method comprises the steps: selecting a test station; determining a flood forecast period l of the test station; constructing a rating curve (shown in the description) of the test station, wherein t is a sampling moment, N is the number of actual measurement stations of the upstream side of the test station, i isthe serial number of the actual measurement stations of the upstream side of the test station, Z<t+l>, Q<t+l> and a<t+l> are respectively are a water level predicted value, a flow predicted value anda flow coefficient of the test station in the forecast period, a<i, t>, Q<i, t>, Ab<i, t> and Z<i, t> are respectively a flow coefficient, a flow value, a water level coefficient and a water level value of the i-th actual measurement station at a moment t, c is an offset of the flow of the test station relative to the water level in the forecast period, Epsilon is a remainder term and approaches to an infinitesimal value, and l is nit greater than the time lag of a flood wave from the upstream side to a downstream side. According to the invention, the real-time stage-discharge relation of thetest station is represented as a function of the water level of the upstream station and the flow at a historical moment, and the method can obtain the more precise result in the real-time flood forecast applications in different forecast periods, and provides a real-time flood forecast level and the forecast precision.