The invention discloses a power-down protecting method and system for improving data safety of a vehicle terminal system. The method comprises the following steps that a, data in the system are classified, and if the data are read-write data, the data are stored in an Eeprom; if the data are read-only data, the data are stored in a Flash; b, when a request for reading a file is received, a source of file data is judged; b1, if the data are the read-only data, the data are read from the Flash; b2, if the data are the read-write data, the data are read from the Eeprom; c, the data in the Flash are written by a manufacturer, and the data are operated only when software needs to be upgraded in the future; d, when the system receives a request for building a file and writing in the file when operating, the data are written into the Eeprom. According to the power-down protecting method and system, through a new storage mechanism, data damage caused by power-down is avoided, data safety of the vehicle terminal system is greatly improved, and the fault rate of a vehicle terminal is effectively reduced.