Abstract: In this study, rubber tree clone PR107 was selected, and the yield and physiological features under microtapping with different concentration of ethylene were compared. The results showed that no significant correlation was found between the rubber yield and ethylene concentration applied by micro-tapping on PR107. Too high level of ethylene couldn't increase yield. The physical deficits, dry rubber content (DRC) decline, and yield fluctuate of rubber tree were induced by micro-tapping with high level of ethylene (greater than 60%). Instead, micro-tapping with low level of ethylene (less than 40%) gave good yield, stable DRC and steady physiological features of rubber tree.