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An aerobic incubation method with a constant temperature was used to investigate the effects of different fertilization measures and soil types on soil nitrogen mineralization characteristics of typical farmland in Northwest China.Four fertilization treatments: no fertilizer (CK), single urea application (U), single organic fertilizer application (M), and urea combined with organic fertilizer (U+M) were set up to explore the dynamic process of nitrogen mineralization in different soil types. And the first-order kinetic equation fitting and correlation analysis were carried out on the soil accumulative mineralized nitrogen. The results showed that fertilization treatments and soil type significantly affected soil ammonium nitrogen, nitrate nitrogen, and accumulative mineralized nitrogen contents. And there were significant interactions between fertilization and soil type. The orders of accumulative mineralized nitrogen content and mineralization rate of different soil types were Lou soil, Loess soil, Yellow River irrigation soil, and Grey brown desert soil. Compared with CK treatment, different fertilization treatments significantly increased soil accumulative mineralized nitrogen, mineralization rate constant (k) and mineralization potential (N0), and the differences among treatments were significant （P<0.05). The accumulative mineralized nitrogen content and mineralization rate of single urea application and urea combined with organic fertilizer were 2.83~6.71 times and 3.83~7.70 times higher than that of CK treatment, respectively. Correlation analysis showed that soil accumulative mineralized nitrogen was significantly and positively correlated with soil organic matter and total nitrogen contents. The results illustrated that combined application of organic and inorganic fertilizers could significantly promote nitrogen mineralization in different soil types in Northwest China, improve nitrogen availability and supply capacity, and help maintain soil mineral nitrogen content, which played an important role in the efficient utilization of farmland nitrogen.