Abstract: The paper dealt with the fermentation technique of an avirulent Ralstonia solanacearum strain FJAT-T8, which was used as plant vaccine against crop bacterial wilt disease. The fermentation process of FJAT-T8 was investigated by determination of on-line and off-line parameters in 50L automatic fermentation container. In order to study the growth fitness of FJAT-T8, the parameters with significantly variation during fermentation process were served as indexes and analyzed with cluster analysis. The multiple linear regression and correlation analysis were also used to analysis the parameter dynamic model and relationship between fermentation factors. Besides, tracing observation of cell morphology was conducted with electron microscope. The results showed that the cell growth cycle of FJAT-T8 could be divided into four periods: 0-16h (adaptation period), 24h (logarithmic period), 32-72h (stationary period) and 80-96h (decline period). The comprehensive evaluation indexes for the best fermentation quality were: fermentation time of 40-48h, fermentation pH of 8.7-8.8 and the dissolved oxygen maintaining steady. The study would improve the fermentation quality, formation of product quality standards and factory production of plant vaccine strain T8.