Abstract: The therapeutic effect of florfenicol, a novel-broad-spectrum antibiotic, against pustule disease of juvenile abalone Haliotis diversicolor Reeve was studied with Myroides odoratus (Flavobacterium odortum) NPB-03 isolate under experimental infection through immersion, wounding or injecting in foot muscle. The results showed that the NPB-03 isolate failed to infect abalone in immersion, and the symptom of pustule disease in wounding infection was more obvious than that in injecting. Florfenicol of 6 gmL-1 bath concentration could decrease effectively mortality in wounding infection, but it was 10 gmL-1 concentration for injecting infection to induce mortality. This result demonstrated it needs high-dose chemotherapeutic agents for diseased abalone infected with pathogenic bacteria.