Abstract: Citrus huanglongbing (HLB) is the most destructive disease of citrus, and there is no effective control agent at the present, but control citrus psyllid, excavation of diseased trees.In this paper, we analyzed the effection of humidity on Citrus Huanglongbing thermotherapy in the field.Our results showed that 30 dnature and moist thermotherapy decrease the average concentration of Las in the leaves by 85%and 3.7%.Furthermore, 90 dnature and moist thermotherapy decrease the average concentration of Las in the leaves by 97%and 38%.In the contrast, the average concentrations of Las in leaves under control were slightly increased after 30 dand 90dtreatments;30d and 90 dhumidification without sheeting increased the average concentration of Las in the leaves by 4.5-fold and8.7-fold, but there was no significant difference with the control.Our results suggest that humidification with sheeting decrease the effect on killing Las significantly and increasing the soil moisture will benefit for the breeding of Las.