The amorphous Nb/Si multilayers were prepared for the interdiffusion study. The temperature dependent effective interdiffusion at low temperature in amorphous Nb/Si multilayer was obtained using in-situ XRD technique. The smaller pre-exponential factor for diffusion coefficient in amorphous Nb/Si multilayer is explained by the trap-retarded diffusion mechanism. In this model, the atomic vibration frequency v is substituted by the average characteristic atomic vibration frequency v because of the presence of defect traps.