Abstract: With rapid development of semiconductor and integrated circuit technologies, and increasing integration level of electronic devices, the characteristic dimension of the microelectronic devices become smaller and smaller. The traditional nonvolatile memory based on charge storage will reach its physical and technical limit. As a kind of new immerging memories, resistive random access memory (RRAM) attracts intensive interests owing to its advantages such as simple structure, compatible with conventional CMOS process, high writing and reading speed, low current of write current etc. This paper gives a brief overview on transition metal oxides thin film based RRAM, including the basic working principles, performance criterions, material issues, resistive switching mechanism, as well as challenges on the way to real applications.