Abstract: In order to clarify the harm of continuous cropping on sugar beet, a comparison test of continuous cropping and raw stubble was carried out by using the monogerm seed and the polygerm seed in the field at the same time. The influence of continuous cropping on root quality and yield of sugar beet was studied. The results showed: (1) the average yield of the tested polygerm seed dropped 22429 kg/hm² and that of the tested monogerm seed dropped 18354 kg/hm²; (2) the average sugar content of polygerm seed dropped 2.58 degree, and that of the monogerm seed dropped 1.36 degree; (3) evenly, K increased 0.37 mmol/100g, Na increased 3.31 mmol/100g and α-N increased 1.04 mmol/100g in the polygerm seed, and K increased 0.15 mmol /100g, Na increased 2.21 mmol/100g and α-N increased 0.39 mmol/100g in the monogerm seed; (4) the increased harmful substance content led to the decline of beet root quality in continuous cropping, and the increase of the sugar loss rate, 0.69 on average for the polygerm seed and 0.47 on average for the monogerm seed; extracted sugar decreased, 3.27 on average for the polygerm seed and 2.17 on average for the monogerm seed; sugar yield decreased, 4996 kg/hm² for the polygerm seed and 3814 kg/hm² for the monogerm seed; (5) leaf spot disease occurred earlier in continuous cropping than raw stubble, and the disease grade was 1-2 higher than that in raw stubble.