The biomass energy of crop straw was calculated from 1978 to 2011 in all counties of Weinan City based on the residue to product ratio, collectable ratio and standard coal equivalence ratio of crops. Meanwhile, the distribution range and spatial change of its gravity center was studied by using gravity center model. The results showed that the annual theoretical resources reserve of crop straw was 3.79×10⁶ t and the annual collected amount was 3.17×10⁶ t, among which 8.81×10⁵ t(the standard coal equivalence) can be used for energy production during 2008 to 2011. Grain straw was the main crop straw resources which occupying 90% of the total amount in which wheat and corn straw accounts for 98%. The biomass energy of crop straw resources in Weinan City was on the rise with fluctuations and its gravity center was moving towards the southwest gradually, but the movement speed became slow from 1978 to 2011. Based on the distribution of the straw resources, Weinan City was divided into the key development and utilization district(Linwei District, Dali and Fuping County), moderate development and utilization district(Pucheng, Heyang, Chengcheng County, Huaxian and Huayin City), the inappropriate district(Hancheng City, Tongguan and Baishui County). The biomass energy factory of the biomass energy of crop straw resources can be set between Dali and Pucheng County and should be next to Linwei District.