Abstract: Regression analysis between dry biomass and the corresponding “effective accumulated temperature” or “effective accumulated precipitation” of 23 years was done using daily temperature and precipitation observations from the past 48 years (1958-2005). The effective temperature (>10℃) showed an obvious upward trend but there were significantly different anomalies. There were no obvious variations of annual precipitation, but anomalies increased significantly (i.e., differed significantly between years). Effective precipitation during the growing season was an important resource and the effective accumulated temperature (>10℃) and effective accumulated precipitation showed a positive correlation (R=0.620 5). The biomass and effective accumulated temperature(>10℃)did not reach significant levels, but effective accumulated precipitation showed a significant positive correlation. The relation of biomass with configurations of effective accumulated temperature and effective accumulated precipitation was Y=71.409+0.334X₁-0.020X₂ and reached significant levels (P<0.001). Suitable configurations of effective accumulated temperature and effective accumulated precipitation played the most important role in the growth of vegetation, while suitable configurations of temperature and precipitation affected productivity of steppe communities in semi-arid areas.