The sufficient condition which guarantees the permanence of the system is obtained by comparison theory of ordinary differential equation.Under certain sufficient conditions

the uniqueness and globally asymptotic stability of periodic solution of the system is proved by Brower fix point theory and Lyapunov function.Moreover

the almost periodic phenomena are discussed

and some sufficient conditions which assure the unique existence and globally asymptotic stability of almost positive solution are deduced.Finally

numerical simulations about the periodic system are given to prove the conclusion to be true.