The invention discloses an optimization method for the injection height of nozzles of a cold-rolling emulsion direct-injection system. The method comprises the following steps of collecting the equipment technological parameters required for optimization of the injection height of the nozzles; initializing the optimal value of the objective function for optimization of the injection height of thenozzles and giving the optimal step size; initializing the optimization process parameter; calculating the injection height of the nozzles; calculating transverse distribution of the flow density of emulsion jetted on the surface of strip steel by one single nozzle; calculating superposed transverse distribution of the flow density of the emulsion, jetted on the surface of the strip steel, of theN nozzles; calculating flow transverse distribution of the emulsion within the width range of the strip steel; calculating the objective function for optimization of the injection height of the nozzles; judging whether F(Hi) is less than Fy or not; judging whether Hi is less than Hmax; and outputting the optimal values of the injection height of the nozzles of the cold-rolling direct-injection system and completing optimization of the injection height of the nozzles of the cold-rolling emulsion direct-injection system. The method has the advantages that the uniformity of transverse distribution of the rolling lubrication performance of the cold-rolled strip steel can be effectively improved, and the defects of the strip shape and the surface quality of a finished product of the strip steelcan be reduced.