The invention discloses a road adhesion coefficient simulation device and method for a bench test of an automobile braking system. The objective of the invention is to provide a road adhesion coefficient simulation method, and the method can be used for precisely simulating various different adhesion coefficients on the test bench. The method comprises the steps: calculating and obtaining the frictional force f0 withstood by a single wheel of an automobile according to a to-be-simulated road adhesion coefficient u0 and a to-be-simulated axle load N0 of the single wheel of the automobile; applying a load G0 to the single wheel of the automobile through a servo oil cylinder, enabling a rotating drum to rotate, gradually increasing the travel of a braking pedal till a tyre slips, collecting the maximum braking force Fmax, comparing the collected braking force Fmax with the calculated frictional force f0, and judging whether the difference between the maximum braking force Fmax and the calculated frictional force f0 is within a set small deviation range or not; Enabling the braking pedal to return to a zero position if the difference is bigger, changing the load applied by the servo oil cylinder, and increasing the position of the braking pedal from zero gradually; repeatedly carrying out the process till the collected difference between the maximum braking force Fmax and the calculated frictional force f0 is within the set small deviation range.