The invention relates to a preparation process and device of a membrane electrode, and belongs to the technical field of fuel cells. The preparation process of the membrane electrode comprises the following steps: preparation of a single-side catalyst layer: firstly immersing a polymer membrane into a catalyst solution, then, pulling the polymer membrane out of the catalyst solution, forming a first catalyst film on one side of the polymer membrane, and heating and rolling the first catalyst film to obtain the polymer membrane coated with the catalyst layer on one side; and preparation of a double-side catalyst layer: immersing the polymer film into the catalyst solution, then, pulling the polymer film out of the catalyst solution, forming a second catalyst film on the other side of the polymer film, and heating and rolling the second catalyst film to obtain the membrane electrode. The prepared membrane electrode has the advantages of high bonding strength with the catalyst and good uniformity; and the method is simple to operate, does not need a complex turnover process, and realizes one-time rapid coating and heating and rolling of the catalyst on two sides of the membrane electrode, so that the production efficiency is improved.