In this paper, the tunable properties of metamaterial absorbers based on 3D Dirac semimetal films (DSFs) in the terahertz (THz) regime are discussed in theory. We consider the absorbers with square-shaped, circular-patch, and cross-shaped resonators. These resonances are theoretically polarization-insensitive at normal incidence because of their 90° rotational symmetry and can achieve perfect absorption in numerical simulation. We then introduce dual-band and broadband absorbers by combining two DSF-based square-shaped (or circular-patch) resonators into one unit cell with different sizes. Unlike with a conventional metal-based absorber, the absorption of a DSF-based absorber can be dynamically tuned by varying the Fermi energy instead of refabricating the structures. Moreover, the DSFs can be regarded as a "Salisbury screen" of an absorber to block the transmission at the THz frequencies, which can be more convenient than graphene in the application of a tunable absorber. Our designs have potential applications in various fields such as sensors, thermal detectors, and imagers.