This paper presents a model based on discrete no-fit polygon for the two-dimensional irregular packing problem. Burke et al. have presented an effective BLF algorithm to solve the irregular packing problem, however, their algorithm might generate invalid results for some special cases. To solve this problem, a model based on discrete no-fit polygon is proposed, and its correctness has been strictly proved. Only points and intervals are only considered by this model, which greatly decreases the geometry complexity of the original problem and makes the problem easily solved by many heuristic strategies. Computational results show that the algorithm based on discrete no-fit polygon model is very efficient.