Cadmium (Cd), a non-essential element of organisms, has been listed as one of the five major toxic heavy metal elements because of its strong mobility in soil and high risk to human body. The migration and toxicity of Cd in soil are closely related to its existence, and soil pH is one of the most important factors affecting the existence of Cd. Therefore, in this paper, the analysis methods of soil Cd morphology were reviewed, and effects of pH on Cd and the mechanism were discussed. Finally, the future research directions are prospected, which could provide references for the treatment and remediation of cadmium contaminated soil.