This paper analyses nitric nitrogen of the greenhouse soil in different service life in Yangling.The result indicated that the content of nitric nitrogen in greenhouse obviously higher than the open crop field,the salt and nitric nitrogen accumulation was obviously on top greenhouse soil,the content of nitric nitrogen trend to increased along with cultivated year.The pH value was dropped by cultivated year;the content of pH was higher in upper layer than in lower layer.There is a significant negative interrelation between pH value and nitric nitrogen,r=0.942 3.The content of nitric nitrogen changed in different growing period,the nitric nitrogen contents begin to decrease after tomato fruit stage,the nitrogen accumulates does not have a notable relation with the general salt and pH during the whole growth period.