Abstract: Soil fertility imbalance, the pathogenic species and numbers accumulation were becoming obvious after a long term continous cropping of crops, which showed continuous cropping obstacle. Continuous cropping obstacle was one of the main restriction factors in potato industry. In order to understand the relationship between soil-borne fungal pathogens and potato continuous cropping, and explore the mechanisms of potato’s continuous cropping obstacle, population dynamics of main fungal pathogens in soil was conducted by dilution plate and debris separation methods. The main fungi groups were Fusarium spp., Verticillium spp. and Rhizoctonia solani in soil of Huichuan in Gansu province, three fungal pathogens were maily distributed in 0-10 cm soil, with lessly in 10-20 cm and 20-30 cm soil. And the increasing year of potato’s continuous cropping, the numbers of fungal pathogens in 0-10 cm soil increased obviously, among which the number of Fusarium spp. in 0-10 cm at potato-bean stubble, potato continuous cropping one year, two years and three years were 3 900, 900, 2 100 and 5 900 per gram soil, numbers of Verticillium spp. were 200, 400, 600 and 1 600 per gram soil, respectively, And Rhizoctonia solani were 7.80, 9.58, 20.60 and 22.40 per ten gram soil. The results suggested that focus on control fungal pathogens in surface soil by ploughing or chemical treatments.