The invention provides a method for establishing a thin-layer oil deposit capacity formula of a narrow river channel. The method for establishing the thin-layer oil deposit capacity formula of the narrow river channel includes the steps that firstly, a typical geologic model of a thin-layer oil deposit of the narrow river channel is established, and a flow line is used for simulation study of the flow form of the oil deposit of the narrow river channel; secondly, the thin-layer oil deposit capacity formula of the narrow river channel is established according to the flow form through the equivalent flowing resistance method; thirdly, sensitivity analysis is conducted on the influence factor influencing the capacity of a single well according to the thin-layer oil deposit capacity formula of the narrow river channel; fourthly, the measure and direction for improving the capacity of the single well is determined according to a result of sensitivity analysis. According to the method for establishing the thin-layer oil deposit capacity formula of the narrow river channel, the capacity of the single well of the oil deposit can be accurately forecasted, and thus a technical support is provided for greatly improving the capacity of the single well for the thin-layer oil deposit of the narrow river channel.