Abstract: As one of the most significant modules of decompilation, data type reconstruction has an important role in readability and intelligibility. This paper proposed an algorithm for automatic type reconstruction from assembly code obtained from the MinGW GCC 3. 4. 5 compiler. The basic types are reconstructed using an iterative algorithm, which uses a lattice over the types' properties. I}he composite types' skeletons arc recovered by establishing label equivalence classes, and the member variables by constructing the set of offsets for each composite type. The algorithm is the essential part of the tool being developed by authors, which not only reconstructs the basic type exactly, but also makes an active research into the hot issue aimed by all researchers currently and it has a favorable outcome.

Key words: Dccompilation, Type reconstruction, Type dependence equation, Equivalence class