Abstract: The state of the internal water in tree xylem is important in tree physiology and has a crucial effect on the quality of standing trees. However, there are several difficulties involved in the accurate and nondestructive evaluation of internal water using acoustic techniques, especially in winter. We reviewed the recent research about ice formation, propagation, distribution and crystal content, which reported both macroscopic tree stem and microscopic wood cell results. The freezing patterns and behavior of intracellular or extracellular water in woody tissue were also discussed. Several methods, including time domain reflectometry, cryo-scanning electron microscopy, differential thermal analysis and nuclear magnetic resonance, were used to study the freezing process of the internal water in wood, and their advantages were compared. Consider that further research is required to develop the technical methods, research objects and depth of analysis. In future, more in-situ detection should be performed on living standing tree trunks and branches using a variety of means to systematically study ice formation and expansion processes. A future aim would be to obtain a clear understanding of the mechanism of ice formation and propagation in wood at subzero temperatures.