The invention discloses a method for 3D printing of the surface of a concrete wall body and application of the method. The method for 3D printing of the surface of the concrete wall body comprises thefollowing specific steps that firstly, concrete for 3D printing is prepared; secondly, a printing head extrudes out concrete, layer-by-layer accumulation is started, the wall body is printed, and meanwhile an additive is sprayed to the surface of the printed wall body; thirdly, when the printed concrete wall body reaches the time of condensing and hardening, a high-pressure water gun is used forwashing non-condensed cement paste on the surface of the wall body till the surface of the wall body is washed down; and fourthly, the concrete wall body obtained after surface washing treatment is subjected to membrane coating curing to the specified age, and the treated wall face has the aggregate exposed decoration effect. The method for 3D printing of the surface of the concrete wall body canbe applied to infrastructure construction, urbanization and shantytowns transformation engineering. The surface of the wall body is directly printed, and construction personnel do not need to be arranged to carry out traditional treatment procedures such as putty leveling and coating spraying on a newly-constructed wall body.