Chinese kale is an important cruciferous vegetable, but the intensive monoculture cropping system and the inappropriate nutrient management cause serious continuous cropping obstacles which severely limits its sustainable production of Chinese kale. Reductive soil disinfestation (RSD), a soil treatment before crop cultivation, can not only effectively suppress soil-borne pathogens, but also improve soil structure, increase soil organic matter, restructure soil microbial community and restore soil microbial activity. An experiment was conducted in the fields with severe clubroot disease incidence in Chinese kale production base in Anning County, Kunming City, Yunnan Province, and three treatments were designed: no treatment control (CK), RSD treatment incorporated with 12 t/hm² sugar bagasse (RSD_BA), RSD treatment incorporated with 6 t/hm² molasses (RSD_MO). Soil chemical and biological properties were measured, and the yield and clubroot incidence of Chinese kale were recorded. Results indicated that RSD treatments (RSD_MO and RSD_BA) significantly improved soil pH and decreased the contents of soil NO₃^--N and available heavy metals as compared to CK. Moreover, RSD treatments significantly enhanced the yields of Chinese kale coinciding with a considerable reduction of clubroot disease incidence, with a yield increase of 268% and 397% and incidence decrease of 37.3% and 56.7% in RSD_MO and RSD_BA treatments, respectively. RSD treatments also increased the ratio of bacteria/fungi (B/F), reduced the population of Plasmodiophora brassicas, and improved soil microbial activity. Particularly, the disinfestation efficiency was up to 90.6% and microbial activity was increased by 2-fold in RSD_BA treatment. Therefore, RSD treatment incorporated with sugar bagasse is effective to improve soil quality, decline disease incidence, enhance crop yields, mitigate the extent of continuous cropping obstacles, and further achieve sustainable cultivation of cruciferous vegetables in a mono-cropping system.