Abstract: In order to reveal the pattern of invasion and epidemic diffusion of citrus huanglongbing (HLB)， population dynamics of diaphorina citri were systematically monitored at several constant sites， and disease general surveys were conducted as well from 2002 to 2010. The results showed HLB in south and east were more serious than that in north and west respectively during invasion period， while disease spread from south to north with a spire upward trend year by year during diffusion period. A longterm movement cycle of HLB containing invasion， rise， highorder， and decline lasted for 10 years approximately， followed by a epidemic trajectory model: P =-00044N2+0056N -00698 (n =9， r =09552**， r001=07977). An early warning could be issued based on the model when weighted incidence of HLB exceeded 1% in next year.

Key words: citrus, citrus huanglongbing (HLB), movement rule, sequential model, forecast and warning