Abstract: The numbers of beta-receptor and pathologic changes of animal lung tissues were observed on experimental RDS rat modal and the prophylactic effect of drugs were studied in sixty male Wistar rats randomized into six groups. In the control and RDS group, normal saline and oleic acid were injected into tail veins respectively. Lexamethasone, salviae mitiorrhizae, ligustrazini and phenobarbitalum natrium were injected intraperitoneally in another four groups 15 minuts before the intravenous injection of oleic acid given separately. The results showed that the numbers of betareceptor in RDS group were decreased markedly, those in cortisone group were similar to control group, and in other three groups they were not different from RDS group. Lung damage were alleviated in all four groups which were given with a prophylactic therapy. The results of this study indicate that there is a positive correlation between the decreasing of beta-receptor numbers and lung damage in RDS. Cortisone is effective to prevent lung damage from RDS by the maintenance of the activity of beta receptor.