This work presents a 1-bit transmission-reflection integrated metasurface (TRIM) to realize a compact terahertz (THz) interferometric imaging system. Conventional systems, which rely on discrete quasi-optical components such as beam splitters and focusing lenses, suffer from bulky volumes and complex alignment. The proposed planar TRIM integrates the dual functionalities of a 50/50 beam splitter and dual-path focusing lenses. Based on the Pancharatnam-Berry (PB) phase principle, two types of rotated meta-atoms are employed to achieve binary (0 and π) phase modulation for both cross-polarized reflection and transmission. Full-wave simulations demonstrate that the designed meta-atoms achieve a polarization conversion efficiency of 96.6% at the target frequency of 165 GHz. A 36 × 50 TRIM array is constructed in simulation, which generates symmetric focal spots on both sides. The full width at half maximum (FWHM) of the simulated focal spot is approximately 2.74 mm (~1.5λ). This integrated design significantly reduces interferometric system volume and energy loss, offering a promising platform for portable and efficient THz imaging in applications such as non-destructive testing, security screening, and biomedical diagnostics.