This study developed two types of Auto-control Hot-water Treater. By using electrical heating system, operaters can control the Treater's tempreture. In the experiments, the variance of mechanical tempreture was not above 1℃. Experiments showed that nearly 100% of bulb mites were killed after Gladious bulbs were treated in 40℃ hot water for two hours, or in 45℃ hot water for a half to one hour. Therefore, Auto-control Hot-water Threater should be a better device than chemical treatments in killing bulb mites.