Extensive investigations into diamond classification, growth structure and impurity have been performed by scientists, but rare studies have been devoted to the diamonds with mixed types. Using DiamondView and FTIR microscopic regional scanning techniques, the authors found that one of the sixteen diamonds collected in 50^# pipe in Liaoning displays both ⅠaB and ⅠaAB types simultaneously. The boundaries between ⅠaB and ⅠaAB types are clear. In DiamondView UV-fluorescence images, the diamond displays an irregular circle-like growth zoning, which could be divided into two growth stages, i.e., early nucleation stage and late growth stage. At the early nucleation stage of the diamond, the growth ring is not apparent and there is no multiple growth center. At the late growth stage, the concentric circling structures is obvious, with clear boundaries between various envelops and uneven fluorescence colors. the shape and intensity of absorption peaks, obtained by the FTIR microscopic regional scanning spectra, are continuously variable. The infrared spectra have basic identical features at the same growth stage, except for the difference in absorbing intensity. The infrared spectrum characteristics are divided into two types, ⅠaB and IaAB , at different growth stages. Pseudo-color mapping of concentration distribution related to total nitrogen and a pair of atoms nitrogen and hydrogen has been obtained by OMNIC Picta. The results of DiamondView and FTIR microscopy regional scan can be mutually validated from center to edge of the diamond, and the change in nitrogen and hydrogen concentrations corre-sponds to two stages observed by the DiamondView image. Based on the study of the variations of nitrogen and hydrogen of the diamond, the authors hold that the growth environment of the diamond underwent apparent changes with a clear growth pause between the two stages and, as a result, A centers could not be completely transformed into B centers at later growth stage. The consumption of nitrogen and hydrogen was remarkably at the nucleation phase, and they were almost completely consumed at last, then the crystal growth stopped until the surrounding environment changed. With the complement of nitrogen and hydrogen, the diamond continued to grow. It is also shown that the concentrations of nitrogen and hydrogen might have played an important role in nucleation. Under low saturation, the growth of diamond might be slower or even stopped. The discovery of this kind of diamond is of great significance in the study of geological environment changes during diamond growth processes.