Human life is seriously threatened by cancer. Long years of study and data collecting have led to a growing body of knowledge about cancer and its treatment. The p53 gene is crucial as a tumor suppressor. With the more in-depth study of the structure and function of p53, the greater relevance of this tumor suppressor gene is understood in the process of suppressing tumor development. Non-coding RNAs (ncRNAs) such microRNAs (miRNAs) that are about 22 nucleotides in length play a crucial role in tumor initiation, progression, and metastasis. In the fight against cancer, miR-34 has emerged as a key player. Tumor development, metastasis, and tumor stem cell maintenance may all be stymied by the regulatory network created by p53 and miR-34. This article summarizes recent developments in our understanding of the p53/miR-34 regulation network and its potential utility in the detection and treatment of cancer.