Background: Precision medicine has emerged with the development of science and technology and the rise of big data. This study first defines and presents the advantages of precision medicine and then introduces the development of three technologies: gene sequencing, cellular immunotherapy, and gene editing. The clinical applications of precision medicine in lung cancer, cervical cancer, breast cancer, and prostate cancer are thus analyzed. Lastly, the existing problems and future development directions of precision medicine are identified. The introduction of gene sequencing, bioanalytical techniques, and big data analysis tools has propelled medicine into the era of precision medicine. Key technologies in precision medicine form the foundation of its development. Therefore, this study elaborates on the development of key technologies in precision medicine, the current status of its clinical application, and the main problems that currently exist. This study also suggests solutions to the problems. Objective: To systematically explain the development and principle of three core technologies in precision medicine and to predict the main research trends of precision medicine. Results: Research in gene sequencing, cell immunotherapy, and gene editing technology has shown significant progress, and accurate medical treatment has achieved remarkable results, effectively prolonging the survival time and improving the quality of life of patients. Conclusion: Precision medicine has made significant achievements, but problems remain. Ensuring safety and efficiency in precision medicine should be the focus of future research.