The invention discloses a construction method of a semi-prefabricated cover beam. The construction method comprises the steps that a cover beam formwork is included, the cover beam formwork is assembled by a plurality of templates, a plurality of hollow pipelines are installed in the templates, a cover beam is manufactured by pouring cement into the cover beam formwork, and the cover beam is hoisted to pier columns for assembly by a lifting device. A thin-walled shell is prefabricated, and after hoisting is completed, steel bars are bound, internal core concrete is cast in place. Holes are reserved in a bottom plate, and are connected with pile foundations during installation, and the cover beam is provided with temporary prestress and permanent prestress. The problems of large weight of atraditional prefabricated cover beam, high requirements for transportation equipment, hoisting equipment, a hoisting space and the like, and large difficulty on applying a prefabricated assembly process under the conditions of urban building intensive areas and the like can be solved; compared with a cast-in-place cover beam, the procedures of arranging supports on site, removing formworks afterpouring and the like are omitted, the quantity of one-time pouring is decreased, and the problem that site management and scheduling are complicated is solved; and compared with a prefabricated steelcover beam, the later maintenance workload is small, and the comprehensive cost is low.