One hundred and seventy children with cough were divied into two groups at random. 120 patient were treated with Zhenkeling oral liquor (ZKL group). The other 50 children were given pectoral syrup (control group). The results showed that the total effective rates of ZKL group and control group were 96.7% and 56.0% respectively, and the markedly effective rates were 80.8%, 18.0% respectively (P < 0.001). Animal experiments indicated Zhenkeling has the effect of relieving cough, reducing sputum and ameliorating asthma; their antibiotic and anti-inflammatory effects were discovered too. The dosage of Zhenkeling was 100 times as clinical dose in acute toxicity test and the dosage was 32, 16, 8 times as clinical dose in long term toxicity test respectively. No adverse action was found in these experiments.