Abstract: For a threespecies clockwise chain predator prey system with Holling Ⅲ functional response, some sufficient conditions which guarantee the permanence of the system were determined by using comparison theory and Liapunov function of ordinary differential equation. Moreover, for the periodic system, it has been proved that under certain conditions there exists a unique positive periodic solution which is globally asymptotically stable. Finally we dicussed almost periodic phonomena, and obtained some sufficient conditions which assure the unique existence and globally asymptotic stability of almost positive periodic solution.

Key words: Holling Ⅲ functional response, positive periodic solution, almost positive periodic solution, globally asymptotically stability