Abstract： A SI-SIR epidemic model with diffusion and delay is investigated.The asymptotic behavior of the corresponding reaction-diffusion equations with homogeneous Neumann boundarv conditions is given using spectral analysis and of constructing the Lyapunov function.Numerical simulations are given to that the disease-free equilibrium is globally asymptotically stable if the contact rate for the susceptible birds and the contact rate for the susceptible humans are small.But if the contact rate for the susceptible birds or the contact rate for the susceptible humans are big,mutant avian influenza spreads in the human world.