The invention discloses a manufacturing method of an outer wall heat-preservation decorating plate with a vacuum heat-insulation function and further provides a flame-retardant material. The manufacturing method comprises two procedures, namely the primer line processing technical procedure and the finishing coat line roller-coating technical procedure. The primer line processing technical procedure comprises the specific steps that 1, constant-thickness sanding and dust removing are conducted; 2, roller-coating of back surface seal coat is conducted, and the back surface seal coat is cured into a first UV seal coat layer; 3, roller-coating of ultraviolet (UV) penetrating agents is conducted for two times; 4, infrared leveling is conducted; 5, the front surface is coated with UV putty, andUV curing is conducted to generate a UV putty layer; 6, roller-coating of the UV seal coat is conducted for three times, and the UV seal coat is cured to generate three second UV seal coat layers; and 7, fine sanding is conducted. The finishing coat line roller-coating technical procedure comprises the specific steps that 1, dust removing is conducted; 2, roller-coating of UV glue is conducted togenerate a first UV glue layer; and 3, UV finishing coat is smeared for five times and cured to generate five UV finishing coat layers. According to the manufacturing method of the outer wall heat-preservation decorating plate with the vacuum heat-insulation function, strong, rapid and deep permeation of UV curing penetrating agents and a fiber-reinforced calcium silicate plate or a fiber cementplate can be achieved, deep curing film-forming is achieved, the UV curing penetrating agents, the UV putty and the UV seal coat form a stereo chemical net-shaped cross-linking reaction, and the adhesive force problem of a decorating face layer and a base plate can be solved. The gluing property of the flame-retardant decorating plate prepared through the manufacturing method meets the national standard requirement, and a base material has the flame-retardant property; the mechanical property of the base material is not affected, the formaldehyde emission is also in the grade E1 or above, andthus safety and environmental protection are achieved; and meanwhile, the natural texture of wood is kept, and the decorating effect is good.