The parameters of unrease kinetics were studied using sixteen samples from seven main soils in ShaanXi Province.The kinetic parameters (V_O、K_m、V_max、V_max、/K_m、K) and the active energy E_a could be used to express the characteristics of unease activity under different conditions of acology,and there were apparent differenoes between the soil samples of high and low fertility.Except for the paddy soil, the V₀,V_max,K and V_max、/K_m of urease in the high fertility soils are all greater than those in the low fertility soils. By means of correlation and principal component analysis, the kinetic parameters V_max、 and V_max、/K_m could act as the indexes of soil fertility;The sequence of average values of E_a showed a difference of enzyme reaction mechanism between high and low fertility soil samples.