The bacteriostasis test which is in vitro of the combination use of heartleaf houttuynia herb and TMP on pathogenic bacterium of yellow scour of newborn piglets was studied.And the bacteriostatic action of the combination use of Chinese herbal medicine and western medicine was investigated. The result indicated that the minimal inhibitory concentration, MIC of heartleaf houttuynia herb and TMP was respectively 1.25g/mL and 1.25mg/ mL; when they were used together, the MIC of them respectively descended to 0.625g/mL and 0.625mg/mL, the antibacterial action was addition effect and the antibacterial effect was significant.