Design of a die-casting die is a critical activity for its manufacturing and further downstream activities. Further, in design of a die-casting die, activities like cavity design, cavity layout and design of gating system are essential components. Design of gating system for a die-casting die is dependent upon a number of parameters which are influenced by part design and die-casting alloy. Gating system design takes much time of the die-casting expert since it requires lot of manual input and a number of iterations to finalize the design. This requires a good knowledge of die-casting process, making this activity completely dependent on the user. In modern day industry lot of CAD/CAM tools are being applied for design, development and manufacturing of a die-casting die. However, dependency on a die-casting expert throughout design and manufacturing of die-casting die makes it a quite lengthy process. Gating system design being one of the major activities in die design also takes much time. Therefore, it would be quite beneficial to automate the activity of the gating system design. This work is about computer aided design of gating system for die-casting die. Proposed system takes CAD file of the die-casting part as input and uses die-casting process knowledge to determine different parameters for the gating system. Designs of the components of the gating system like runner, gate and overflow have been attempted. A feature library has been proposed as a part of this work which together with parametric design of the gating system generates CAD model of the components of the gating system. The system has been tested on a number of industrial parts and results found are quite encouraging. The system would go a long way in bridging the gap between designing and manufacturing of die-casting.