Abstract: In the process of rapid prototyping based on welding, heat input has great effect on the quality and capability of workpieces. Time interval of deposited layers is used as a method of controlling the heat input in rapid prototyping process of 5356 Al-alloy based on AC gas tungsten arcwelding (AC-GTAW).Under the condition of various time interval of deposited layers, the surface morphologies and microstructures of deposited layers are better than that in equal time interval of deposited layers.