By planting a susceptible Chinese vegetable in the seedling bed irrigated with Plasmodiophora brassicae Woronin contaminated water from floatation culturing system (FCS) and inoculated with the resting spores of the pathogen, the pathogenicity was analyzed in water and soil, the spread distance of the pathogen and clubroot disease severity in the soil with different water contents and irrigated with different resting spores water was investigated, and chemicals were screened in the FCS for the disease control. The results showed that FCS inoculated with the pathogen favored the disease spread, and disease severity was positively related to the inoculum number. Disease incidences were 9.51%,19.88%, 44.31%, 63.65% and 76.00% in FCS and 5.33%, 15.00%, 20.67%, 43.33% and 45.00% in traditional soil culturing system when 103, 104, 105, 106，107 spores/g were inoculated onto Chinese cabbage respectively. Chinese cabbage became diseased when it was seeded in the culture substrate with 38%-115% water content, but the culture substrate with 77% water content best benefited the disease. When the plants growing in the substrate were 5 cm and 10 cm far from the pathogen, the disease incidence were 20.43% and 10.23% respectively. The active ingredient of 375.0 mg/L chlorothalonil WP, 250.0 mg/L carbendazim WP, 25.0 mg/L cyazofamid SC, 125.0 mg/L fluazinam SC and 262.5 mg/L BAS651F were applied to the FCS, they could control 96.65%, 94.19%, 87.93%, 80.18% and 88.02% of the disease, respectively, but fluazinam SC and BAS651F inhibited the plant growth when their concentrations were used in this experiment.