The invention discloses a method for installing and constructing external wall dry-hanging stone, and relates to the technical field of external wall dry-hanging. The method for installing and constructing the external wall dry-hanging stone comprises the following steps that S1, in the construction process of the external wall dry-hanging stone, after keels are installed, T-shaped connecting pieces are manufactured or purchased, and the T-shaped connecting pieces are installed on the keels through bolts. According to the method for installing and constructing the external wall dry-hanging stone, the safety and firmness of the dry-hanging stone can be effectively improved, the installation difficulty of the dry-hanging stone is reduced, material loss is reduced, it is guaranteed that the installation quality of the external wall dry-hanging stone meets the requirement, therefore, the safety and the finished product impression of the dry-hanging stone are guaranteed, and the method is simple, practical, convenient to construct and capable of saving working hours, reducing construction cost, improving safety performance and guaranteeing the attractive effect of finished products.