Abstract: To address limitations in dynamic beam shaping, a modulation mechanism based on strong coupling between Moiré superlattices and microcavity photons was proposed. By combining Density Functional Theory with quantum coupled mode theory, the interaction between Moiré excitons in a 2.0°-twisted Cs-doped WS₂/MoS₂ heterojunction and high-Q (Q=2 000) cavity photons was analyzed. Calculations indicate the system operated in the strong coupling regime, where the resulting polariton states exhibited high sensitivity to external electric fields. Remarkably, the device achieved continuous phase modulation exceeding 180° (π-shift) in its reflection spectrum. These results demonstrate the feasibility of manipulating cavity polaritons via Moiré superlattices for beam shaping, providing a theoretical basis for designing novel reconfigurable spatial light modulators.