Caries is an infectious disease in which the invasion of pathogens and their metabolites can activate the recognition and defense system of the pulpodentinal complex. In-depth understanding of the immune responses mediated by the pulpodentinal complex will help to estimate the real state of the dental pulp during the progression of caries and to take reasonable clinical treatment strategies, which can be more targeted and less invasive. Based on the physiology of the pulpodentinal complex, the present article introduce its immunocompetence and mechanism, reactive changes, clinical intervention and its significance during the caries progression, as to improve diagnostics as well as treatment strategies for caries.