Infrared (IR) nonlinear optical (NLO) materials are the key devices for generating tunable infrared output between ∼3 and ∼20 μm by laser frequency conversion techniques. Based on the study of structure and properties, chalcogenides, pnictides and oxides, have been demonstrated as the most promising systems for the exploration of new IR NLO materials with excellent optical performances. Over the past decades, many state-of-the-art IR NLO materials have been discovered in these systems. In this work, the synthesis, characterization and performance of the new developed promising IR NLO materials are summarized and analyzed. The typical IR NLO materials with large-size single crystals are selected as the representatives for the detailed discussions. Moreover, the discrepancies in optical properties of single crystal, polycrystalline powders, and the corresponding calculated results are discussed, aiming to provide suggestions for the exploration of next generation IR NLO material in these systems.