[Aim] The Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus is one of the major diseases in citrus. Exploring the influence factors of HLB occurrence and harm in Guangdong Province can provide the basis for scientific prevention and control of this disease.[Method] The incidence and distribution of HLB were investigated by a real-time PCR and conventional PCR for various citrus cultivars grown under different climatic, environmental and geographical condition and culture practices in citrus production areas, including Huizhou, Zhaoqing, Yunfu, Jiangmen, Yangjiang, Qingyuan and Shaoguan in Guangdong Province, China.[Result] The incidence of HLB on different cultivars were:Hongjiangcheng 78.05%, Mashuiju 76.04%, Shatangju 73.20%, Gonggan 69.30%, Nianju 63.00%, Shatianyou 58.68%, Ningmeng 56.96%, and the incidence of this disease on different root stocks were:Suanju 15.30%, Zhike 6.57%, Ningmeng 4.43%. Other factors such as low latitude, high temperature, more typhoons, location near the mountain, high density planting, and poor disease management were also associated with high incidence.[Conclusion] Apart from natural causes (low latitude/high temperature/more typhoons, plain terrain), several management-dependent factors were conducive to the prevalence of HLB. It is possible to mitigate the damage by improving orchard management practices.