The invention relates to a decorative building material, in particular to an imitation stone for an outer curtain wall, and also provides a production method of the imitation stone for the outer curtain wall. Aiming at solving the problems of an existing outer curtain wall that line equidensity of granite and marble is high, weight is heavy, mounting is complex, chromatic aberration is obvious andprocessing speed is slow, a ratio that the imitation stone comprises 18-25% of cement, 17-22% of quartz sand, 17-24% of quartz powder, 16-22% of fibers and 16-21% of fine stuff is adopted, so that the imitation stone for the outer curtain wall is reduced by about 30% in density compared with existing natural stones such as the marble, and price is reduced by about 40%; and meanwhile, the processing speed is high, energy is saved, labor cost is also greatly saved, strength is equivalent, and the fiber ingredient is added, so that a thin plate made from the product of the invention hardly cracks, mounting benefit and speed are improved by about 30% during mounting, construction period is greatly shortened, and the labor cost is saved.