Observation of arbuscular mycorrhizal (AM) colonization status and measurement of colonization percentage is an important fundamental work in mycorrhizal research. Methods for root staining and quantifying AM colonization percentage is reviewed, compared and evaluated in this paper. Ink-vinegar staining method observing colonization status, root-segment colonization weighting method, and magnified intersections method measuring colonization percentage, are considered to be appropriate approaches in AM studies with greater scientific, accurate and feasible values when compared with other methods. Different observation methods can be used for different purposes. For example, magnified intersection method could be chosen to observe and measure the arbuscule development status of AM fungi, whilst direct counting method could be employed to count the numbers of vesicles and entry points per unit root length. Thus the research results obtained for specific purposes are comparable. It is necessary to establish molecular techniques and fatty acid quantitative method to measure colonization status of one or more species of AM fungi, which will promote studies in physiological and ecological function.