The vacuum tube method has been used for the construction of nondestructive and physically stable graphitic carbon nitride/graphene nanoplatelet composites and their photocatalytic behavior studied by measuring different photoactivities, such as photocurrent, photoluminescence, and the photodegradation of tetracycline hydrochloride under visible‐light irradiation. The formation of a heterojunction was confirmed by XRD, TEM, SEM, FTIR, XPS, and Raman spectroscopy. The results of this research indicate that the vacuum tube method is a facile, economic, and environmentally friendly approach to the preparation of composites. An ion‐trapping experiment indicated that, under visible light, the most effective photocatalyst generated the superoxide radical (O2·–) and holes (h+) to achieve the complete degradation of tetracycline hydrochloride. [ABSTRACT FROM AUTHOR]