Owing to its excellent properties, cubic aluminum nitride (c-AlN) is an ideal material for optoelectronic devices such as light-emitting diodes and laser diodes. In this study, the c-AlN/TiN/Si(100) heterostructure is deposited using the laser molecular beam epitaxy technique, and its microstructure and optical properties are investigated. The experimental results show that the AlN film and the TiN buffer layer both show a (200) preferred orientation of cubic rock-salt structure. The interfaces between the c-AlN film, TiN buffer layer, and Si substrate are clear; a second phase is not observed. However, there are certain defects at the interface owing to mismatched stress. The photoluminescence spectrum of c-AlN film exhibits three emission peaks at approximately 376, 520, and 750 nm. The emission peak at 376 nm is related to nitrogen vacancy (VN) and oxygen impurity (ON). The emission peak at 520 nm is related to the recombination of Al vacancies (VAl) and ON. The emission peak at 750 nm can be attributed to the radiation recombination between VAl and the valence band. The electroluminescence emission peak of c-AlN film is approximately at 580 nm, and it is attributed to a deep-level defect emission.