The invention provides a balcony-railing type solar thermal collector, which comprises a bottom plate, two lateral frames, a transparent cover plate and a heat collecting plate core, wherein the bottom plate and the two lateral frame are bent by using one metal plate to form an integral frame; at least one layer of reinforced panel is also arranged between the heat collecting plate core and the bottom plate; two ends of the reinforced panel are respectively and fixedly connected with the two lateral frames and are adhered with the two lateral frames and the bottom plate into a whole through polyurethane insulation coatings; groove-shaped reinforced plates are respectively coated on the periphery of the integral frame; and outer sides of four corners of the lateral frames are respectively provided with a connecting handle which can be connected with a railing connector of a building balcony in a matching way. According to the balcony-railing type solar thermal collector, the integral structural strength, in particular the transverse bearing load is remarkably increased; the solar thermal collector can be directly abutted with the balcony railing of the building; the solar thermal collector can be subjected to modularized assembly instead of the traditional tempered laminated glass used on the balcony; and the balcony-railing type solar thermal collector has the advantages of convenience for installation, practical structure, attractive appearance and capability of saving materials used for balcony railings of buildings.