RNA binding proteins (RBPs) play a key role in gene regulation and participate in life activities such as RNA synthesis, alternative splicing, modification, transport and translation. It is necessary to study the interaction between RNA and RBP into explore RNA functions. The changes of RBPs are related to a variety of diseases. Musashi (MSI) family is a class of evolutionarily conserved RBPs including MSI1 and MSI2, which play an important role in many key processes such as tumorigenesis, progression and drug resistance. They were found to be overexpressed in many tumors and associated with prognosis in the blood system, nervous system, digestive system, respiratory system, etc. MSI binds to mRNA to regulate translation and mRNA stability. MSI maintains the number of cancer stem cells and affects tumor proliferation, invasion, metastasis and drug resistance. The preliminary research of MSI gene as a target to guide tumor therapy has achieved some results. This article describes the physiological functions of MSI family and its roles in tumorigenesis and development, and provides an overview of the latest research progress of MSI family as a diagnostic marker or a therapeutic target.