The invention discloses a three-dimensional positioning decoration construction method for spiral staircase stone facing. The method includes the following steps that a BIM informationized model is established, stone facing part machining parameters are output, stone facing parts are machined, the parts are labeled with serial numbers, a construction assembly map is made, spatial accurate position guaranteeing a construction reference face and stepping layers is established, a three-dimensional measurable spatial coordinate system for improving installing accuracy is established, a spiral staircase civil engineering base body is corrected, a base body framework on which the stone facing parts are installed is established, and the stone facing parts are positioned and installed. The stone facing parts are quantitatively machined as a whole, and the material utilizing rate is increased by 30%; according to the construction assembly map, difficult machining of a spiral staircase becomes easy, production efficiency is improved, 30% of the construction period is saved compared with an existing construction method, on-site stone cutting is not needed, and pollution of dust, raising dust, noise and the like on a construction site is avoided; due to the establishment of the three-dimensional measurable spatial coordinate system, it is guaranteed that the wholly-machined stone facing parts are flat and totally attached to one another.