Methods: Seven English and Chinese databases were used to search for qualified experimental studies as of July 27, 2020. All data were extracted directly from the included studies, and no special conversion formula was used. The weighted mean difference (WMD), 95% confidence interval (CI), and odds ratio (OR) were used for evaluation. Results: Forty-two studies involving 3793 subjects met the qualification criteria. For common pneumonia, a short duration of flu-like symptoms (WMD = -1.81, 95% CI = -2.12 to -1.50, P < 0.001), sputum (WMD = -1.10, 95% CI = -1.50 to -0.70, P < 0.001), pulmonary rale (WMD = -2.03, 95% CI = -2.74 to -1.31, P < 0.001), pulmonary imaging improvement (WMD = -1.88, 95% CI = -2.28 to -1.47, P < 0.001), curative effect (OR = 3.65, 95% CI = 2.81 to 4.76, P < 0.001), and healing period (WMD = -1.68, 95% CI = -2.62 to -0.74, P < 0.001) were associated with the Lianhua Qingwen group; subgroup analysis based on flu-like symptoms showed statistically significant improvements in fever and cough. For COVID-19 pneumonia, improvements in flu-like symptoms (OR = 3.18, 95% CI = 2.36 to 4.29, P < 0.001), shortness of breath (OR = 10.62, 95% CI = 3.71 to 30.40, P < 0.001), curative effect (OR = 2.49, 95% CI = 1.76 to 3.53, P < 0.001), healing period (WMD = -2.06, 95% CI = -3.36 to -0.75, P = 0.002), and conversion of severe cases (OR = 0.46, 95% CI = 0.27 to 0.77, P = 0.003) were associated with the Lianhua Qingwen group; subgroup analysis indicated statistically significant improvements of fever, cough, fatigue, and muscle pain in the Lianhua Qingwen group compared to the conventional drug group. Regarding adverse reactions, no significant difference was detected for common pneumonia (OR = 0.75, 95% CI = 0.54 to 1.05, P = 0.097). Conclusions: Lianhua Qingwen combined with conventional drugs may be a promising therapy for treating common pneumonia and COVID-19 pneumonia.