Abstract: Interface has great influence on the creep properties of composites. A theoretical analysis model was established for aluminum silicate short fiber reinforced AZ91D magnesium matrix composites on the basis of test analysis, and by using 3D finite element analysis method, the effects of interface properties, stress and strain distribution on the interface and short fiber orientation change on the creep properties of aluminum silicate short fiber reinforced AZ91D magnesium matrix composites were systematically investigated. The research shows that the interface properties such as thickness and modulus, have effects on the maximum fiber axial stress and steady-state creep rate. The maximum fiber axial stress decreases with the increasing of interface thickness, and increases with the increasing of interface modulus. The steady-state creep rate increases with the increasing of interface thickness, and decreases with the increasing of interface modulus. Both remain unchanged when the interface modulus is bigger than the matrix modulus. The short fiber orientation also affects the distribution of the axial stress and steady-state creep rate. There is a greater stress and strain on the interface of the fiber end where microcracks are easily produced, which decreases the creep resistance of the material. The interface can affect creep curves and creep fracture mechanism of aluminum silicate short fiber reinforced AZ91D magnesium matrix composites, and the impact is also related with short fiber orientation.