As a novel targeting drug delivery system, acid-sensitive micelles have many advantages, such as increasing solubility of lipophilic drugs, acid-sensitive release, high drug loading, etc.  They can load drugs though non-covalent encapsulation and covalent conjugation methods.  In tumor tissues, drugs are released quickly from the depolymerized micelles with lipophilic copolymer protonation or lypohydrophilic copolymer hydrolysis and covalent conjugated drugs are released when the acid-sensitive covalent linkage breaks.  This review mainly advances acid-sensitive micelles for the tumor targeting drug delivery systems from drug-loaded methods and release mechanisms.