Objective To compare the effect of high-frequency chest wall oscillation (HFCWO) expectoration and mechanical vibration (MV) expectoration in elderly patients with pulmonary infection. Methods Thirty elderly patients with pulmonary infection were randomly divided into a HFCWO group and a MV group with 15 patients in each group. On the basis of routine treatment, the HFCWO group was treated with HFCWO vest to help expectoration, and the MV group underwent traditional mechanical vibration to help expectoration. The respiratory rate, peripheral oxygen saturation (SpO2), activities of daily living (ADL) score were measured before treatment (D1), 7 days (D7), and 14 days (D14) after treatment. Results Except ADL score had no difference between D7 and D14 in the MV group, there were significant differences in daily amount of sputum, respiratory rate, SpO2, ADL score between D1, D7, and D14 in both groups (P<0.05). There were no significant differences in daily amount of sputum between two groups on D1, D7, or D14. SpO2 and ADL score were significantly higher in the HFCWO group on D7 and D14 compared with the MV group (P<0.05). Conclusions Both high-frequency chest wall oscillation and mechanical vibration are effective in improving expectoration. The HFCWO vest is superior in improving blood oxygen and relieving shortness of breath than mechanical vibration expectoration.