The invention belongs to the technical field of electrolysed water and particularly relates to a preparation method of an electrode membrane. According to the preparation method of a solid polymer membrane electrode, creatively, the surface of a proton exchange membrane is coated with a catalyst, and the membrane surface is covered incompletely; and then the membrane surface is etched through an anisotropic etching method under protection of catalyst particles, the catalyst is coated again after pores are formed or a comb-finger-shaped structure is formed, and thus the catalyst particles are attached to the positions, in the pores, of the membrane surface or the membrane surface of the comb-finger-shaped structure. By means of the preparation method provided by the invention, the electrochemical activity specific surface area of the anode catalyst of the membrane electrode can be improved remarkably, multiple relations between the catalyst particles and a water channel, an electronic channel, a proton channel, a gas channel and the like of an electrochemical reaction are exploited, and finally, the purposes of increasing the catalyst utilizing ratio, reducing catalyst carrying capacity and substantially reducing preparation cost of membrane electrodes are achieved.