Abstract: In order to study the effect of different tobacco planting systems (green manure-tobacco with crop rotation, monoculture-tobacco, wheat-tobacco with crop-rotation and inter-cropping) on soil enzyme activities, soil samples were taken from brown soil in Yishui county, Shandong Province. Results showed that in the study period (from 24 Mar to 7 Sep in 2009), the soil catalase, sucrase and urase activity in plowed layers (0-25cm) were not significantly different under different planting systems. However, three soil enzyme activities varied with seasons differently. The activity of catalase changed with a small fluctuation in overall, but reached the minimum after 30 days of the flue-cured tobacco transplanting (20 Jun). Sucrase activity decreased after 30 days of the flue-cured tobacco transplanting, then it gradually increased, and reached the maximum at the harvest period (7 Sep.). Urase activity reached the maximum at squaring stage (68 days after the flue-cured tobacco transplanting) and then dramatically decreased. In terms of the different soil layers (0-5 cm, 5-15 cm, 15-25 cm), the catalase and urase activities increased with soil depth in the plowed layers, but the range was very small. The order of protease activity with soil depth was 5-15cm >0-5cm >15-25cm. In the whole growth period of flue-cured tobacco, the temporal variability of three soil enzymes was also analyzed. Soil urase had the largest temporal variation coefficient, which meant it had the largest effect by the outer environment in the whole tobacco growth period. Soil sucrase took the second place. Soil catalase had the smallest temporal variation coefficient, with a most stable seasonal variation.