Abstract: The effects of different nitrogen levels on soluble sugar, sucrose, fructose and starch content were investigated, providing a theoretical basis for the best technique of nitrogen management in sugar beet production. A field experiment was carried out using sugar beet cultivar H003 as experimental material. Seven N application rates were designed: 0, 40, 80, 120, 160, 200, 240 kg/hm2. The results showed that, at the same nitrogen fertilizer rate, the content of soluble sugar increased firstly and decreased subsequently as the developmental process went on; the sucrose and fructose content presented a trend of decreased-increased-decreased; the starch content was adverse with a trend of increased-decreased-increased. At early growth stage, the content of soluble sugar decreased firstly and increased subsequently by the N application, at late growth stage, the result was adverse; N application rate of 120-160 kg/hm2 in sugar beet leaves could help increase the accumulation of sucrose and fructose content and also advance the peak value of starch. Comprehensive considering the results, at the same nitrogen fertilizer rate, soluble sugar content decreased firstly and increased subsequently, which was consistent with sucrose and fructose content, yet starch content was adverse with all of them; N application rate of 120-160 kg/hm2 was beneficial for assimilation metabolism, translocation metabolism and accumulation metabolism of sugar beet.