Abstract: Three protected vegetable fields with different planting years（0 year, 13 years and 21 years） were selected for a 36 days incubation experiment, four fertilization treatments were set for each planting year to measure soil ammonium nitrogen, nitrate nitrogen and mineral nitrogen content during the incubation, in order to study the effects of planting years and exogenous nitrogen additions on soil mineral nitrogen content.The results showed that during the incubation, the contents of ammonium nitrogen, nitrate nitrogen and mineral nitrogen in soil increased with the increasing planting years of protected vegetables, while the effects of nitrogen application on the increment of soil mineral nitrogen content gradually weakened.The maximum increment of soil mineral nitrogen content in protected vegetable fields with the planting year of 0 year,13 years and 21 years were 90.77 mg·kg^-1,83.66 mg·kg^-1 and 74.03 mg·kg^-1,respectively.The nitrification rate constant decreased with the increase of planting years.Under the same planting year,the contents of ammonium nitrogen,nitrate nitrogen and mineral nitrogen in soil increased with the increase of nitrogen application rate.Under the same nitrogen application,mineral nitrogen content in the treatment of the combined application of organic and inorganic fertilizer was slightly lower than that of all inorganic nitrogen fertilizer treatment.The nitrification rate constant of different N fertilization treatments showed the similar trend.The soil mineral nitrogen content could be directly regulated by the change of nitrogen application amount and fertilizer type,and the loss of nitrogen could be reduced.