Abstract: An experiment of four fertilization treatments in sugar beet field was conducted to study the spatialtemporal variability characteristics (0- 90 cm surface soil, from May to September) of black soil inorganic nitrogen (ammonium nitrogen and nitrate nitrogen) and organic nitrogen content (hydrolizable nitrogen, ammoniac nitrogen, amino sugar nitrogen, amino acid nitrogen, unknown nitrogen and unhydrolysable nitrogen) in the whole sugar beet growth season. The results showed that nitrogen fertilization treatment had impact on the spatial and temporal variation of ammonium nitrogen and nitrate nitrogen in soil. The content of nitrate nitrogen in soil was mainly distributed in 0-50 cm layer and higher than that of ammonium nitrogen in soil. Compared with controls, contents of ammonium nitrogen and nitrate nitrogen in 0-30 cm surface soil were increased by nitrogen fertilizer treatment at sugar beet seedling stage, and consumption of nitrate nitrogen in 0- 70 cm surface soil was increased at the root sugar accumulation stage (July). Compared with no nitrogen fertilizer treatments, the contents of hydrolizable nitrogen, ammoniac nitrogen and amino acid nitrogen in soil were increased in 0- 30 cm layer by applying nitrogen fertilizer. The contents of hydrolizable nitrogen, ammoniac nitrogen and amino acid nitrogen in the soil space of 0-90 cm were obviously decreasing in a gradient, and the content of soil amino acid nitrogen could be balanced in 0-50 cm layer by nitrogen treatment. The content of soil ammoniac nitrogen in soil presented a first increase and then decrease rule along with the sugar beet growing and that of amino sugar nitrogen in soil had no significant spatial and temporal change. The content of unknown nitrogen had opposite change tendency to that of ammoniac nitrogen, amino sugar nitrogen and amino acid nitrogen in soil as the time went on. Soil unhydrolysable nitrogen appeared deep layer residues in nitrogen fertilizer treatments and leisure treatments soils at later growth stage of sugar beet. Except amino sugar nitrogen and amino acid nitrogen, the contents of organic nitrogen components in soil followed the curve equation of the distribution of three times with time variation law of sugar beet growing stage. Hydrolizable nitrogen, ammoniac nitrogen and amino acid nitrogen of organic nitrogen components in soil were major contributors for inorganic nitrogen in growth period of sugar beet.