Optical metasurfaces, with their capability to flexibly control the optical field at the subwavelength scale, have emerged as an ideal platform for achieving high-quality factor (Q-factor) resonances and tunable chiral responses, which are of significant importance for advancing chiral photonic devices. This study proposes a tunable chiral germanium metasurface based on bound states in the continuum (BIC). The structure consists of periodically arranged square germanium nanopillars with double concave grooves, situated on a reflective cavity incorporating a Bragg mirror composed of alternating stacks of Si and SiO₂, thereby forming a single-port system. First, the Q-factor and band structure near the Γ point are investigated through eigenmode analysis, revealing that the Q-value tends toward infinity at the Γ point, exhibiting the characteristics of an ideal symmetry-protected BIC. By breaking the in-plane C₂ symmetry, the ideal BIC is transformed into a quasi-bound state in the continuum (q-BIC), thereby exciting resonance modes that support chiral responses. The far-field polarization states at δ = 0 nm, δ = 20 nm, and δ = 35 nm are characterized, and analysis of topological charges in momentum space reveals that the unique topological properties of the q-BIC originate from the intrinsic resonance of the metasurface. To investigate the chiral response, tuning the asymmetric parameter δ enabled the co-optimization of an ultra-high Q-factor (Q = 6121.14) and strong circular dichroism (CD = –0.94) in the near-infrared band. This demonstrates the feasibility of integrating high Q-factor and pronounced chirality within a single structure. Further adjustment of the center spacing Δd of the double concave grooves achieves inversion of the CD sign, providing a clear theoretical mechanism for the controllable design of chiral states. Multipole scattering power analysis reveals that the magnetic dipole dominates the chiral q-BIC mode. In addition, by introducing a graphene layer onto the structural surface and modulating the Fermi level to alter material loss and dispersion, significant tuning of the CD value is achieved over the range of –0.230 to –0.952 (tuning depth 0.722), thereby expanding the application potential of tunable chiral devices. This research presents a novel approach for developing high-performance, controllable chiral photonic devices. The proposed structure combines the strong field localization afforded by a high Q-factor with chiral flexibility achievable through geometric parameters and electrical tuning, demonstrating substantial application potential in chiral optoelectronic devices.