The invention relates to a construction method, and particularly relates to a construction method of a cast-in-situ reinforced concrete column. The construction method of the cast-in-situ reinforced concrete column is characterized by comprising the following processes: preparatory work of construction, design and manufacture of an assembly type cement mortar annular cushion block, design and manufacture of a template fixing device, measurement and positioning setting-out, wiping of a polymer cement mortar positioning slurry-resisting Hom station, installation of a base and outer supports of the template fixing device, manufacture and colligation of column reinforced steel bars and installation of the protective layer cushion block, installation of a template fixing device operating platform and construction of a template, pouring of concrete, and removal of the column template and the fixing device. The positioning slurry-resisting Hom station wiped around a column root part not only plays a role of positioning the template, but also solves a quality common problem of column root part concrete leakage. With research and development use of the reinforced concrete cast-in-situ template fixing device, any auxiliary scaffold or template fixing frame is not required to be built during the construction. The fixing device has the advantages of repetitive use and low cost, and has the characteristics of convenient operation, high efficiency, and safety.