Abstract: Organoid is a three-dimensional in vitro cell structure formed by normal or tumor specific stem cells under the condition of three-dimensional culture.It has the ability of self-renewal and self-organization to form "micro-organs" similar to the original tissue, which can well recapitulate the characteristics and cell heterogeneity of the source tissue.As a preclinical model for tumor research, organoid can be used for drug screening, predicting patients' response to treatment, and selecting the most appropriate treatment for patients.In addition, it can also be modified to study the mechanism of tumor development and metastasis.As a novel technique, organoid can provide guidance for personalized medicine and has a broad application prospect.In this review, the mechanism of organoid in tumor development, the role of drug screening and clinical treatment, and the application of organoid in tumor microenvironment are briefly reviewed.