According to statistics from 1991 to 2005 in Tongwei County,factors which impacts modern agricultural development were analyzed by the principal component analysis.The results can be grouped into three aspects: agricultural modern level,the population quality and quantity and land productivity.At the same time,the grey correlative degree was used to analyze these factors.We brought forward some countermeasures,e.g.,increasing investment in agricultural science and technology,rational utilization of chemical fertilizers,and promoting the level of agricultural modernization;the protection of arable land,increase the sown area of crops and cash crops;strictly controlling population growth,vigorously developping,science and technology,and education,etc.