The invention discloses a method for optimizing the regulating and controlling efficiency coefficient of a board shape controlling actuator of a cold rolling mill, which comprises the following steps of: building a board shape regulating and controlling power coefficient priori value table under different rolling work points, wherein in the table, one set of band steel width value and a rolling force value correspond to one rolling work point; defining a boundary work point of the table according to the position of the practical rolling work point in the table; setting a weight factor according to the similarity level between a boundary work point parameter and a practical rolling work point parameter; and stacking the priori power coefficient of a boundary point in a weighting way to obtain the board shape regulating and controlling power coefficient under the practical rolling work point. By continuously improving the precision of the board shape regulating and controlling power coefficient with the on-line self-studying model and the practically-tested board shape data, the method can obtain the precise regulating and controlling power coefficient of a board shape adjusting mechanism, applies the precise regulating and controlling power coefficient into a closed-loop board shape control system, and has higher board shape controlling precision.