The effects of fertilization under rain-fed condition and supplemental irrigation after fertilization on dry matter accumulation, yield, sugar production and nutrient absorption of Beta vulgaris L. were studied in order to provide a theoretical basis for fertilization and irrigation in Beta vulgaris L. cultivation. A field-plot experiment was carried out and three treatments were setup, including rainfed without fertilization (CK), rainfed and fertilization (TY), and supplemental irrigation and fertilization (TB), and each treatments with three repetition. The results show that, in the harvest period, TB significantly increases the total dry matter accumulation and sugar yield compared with TY; TB and TY significantly increase the aboveground and total dry matter accumulation, yield, sugar rate and yield compared with CK; TB significantly increases the underground, aboveground nitrogen and total nitrogen and total potassium uptake of Beta vulgaris L. compared with TY; TY significantly increases total nitrogen and total potassium uptake compared with CK; TB significantly increases the underground, aboveground dry matter accumulation and total phosphorus uptake compared with TY; TY significantly increases the aboveground dry matter accumulation and total phosphorus uptake compared with CK. Comprehensive analysis shows that TB is beneficial to promote the growth, development, yield, sugar production, phosphorus absorption, and to reduce nitrogen and potassium absorption of Beta vulgaris L. compared with TY, thus, it is recommended to carry out appropriate artificial supplementary irrigation in May—June when drought occurs.