Through gradual regression analysis to ten kinds nutritions of soils of 54 counties, Saanxi province, the optimum regression modelfor soil utritions(including alkaline--N, quick action Ps quicick ackac-tion K, B and Zn) has been set up, It shows that soil fertility is thelimit factor of wheat production in Guanzhong plain, but this is not ase in North Shaanxi loess plateau gully hill region, Finally，correlation analysis and fuzzy cluster on soil nutriments have been done,From above mentioned, we can get a lot of information about wheat production,soil assessment and nutrition diagnosis