This study is dedicated to enhancing the photocatalytic performance of rod-like ZnO via surface modification with Pd and PdCu nanoparticles, with the goal of extending its spectral response and suppressing the recombination of photogenerated charge carriers. Rod-shaped ZnO was synthesized via the solvothermal method, with the total metal mass fraction controlled at 3%. The structural and optical properties of Pd/ZnO and PdCu/ZnO were comparatively investigated and correlated with their catalytic performance. Experimental results demonstrated that both Pd and PdCu modifications triggered a localized surface plasmon resonance effect, which facilitated the separation of photogenerated electron–hole pairs and enhanced visible-light harvesting efficiency. Compared with PdCu/ZnO, although Pd/ZnO exhibits a wider band gap and a lower proportion of oxygen vacancies, it demonstrates a stronger separation capability for photogenerated carriers and thus achieves higher degradation efficiency. After 30 minutes of light irradiation, the RhB degradation rate of Pd/ZnO reaches 99.7%.Moreover,Pd/ZnO possesses excellent stability, with the degradation rate remaining at 96.9% after five cycling tests.