The invention relates to a data erasable method of memory in smart cards and smart cards thereof, which includes: when a CPU in the smart card determines a data erasable operation will be proceed in the specified memory of the smart card, cache the data to be written in a random memory cache of the specified memory; after sending a data erasable signal to the specified memory, control itself to enter a standby sleep mode. The data erasable signal is used to indicate the specified memory to process the data erasable operation by obtaining the data to be written from the random memory cache. Using the provided solution, the current of the machine card interface can be reduced when a data erasable is proceed in the specified memory of the smart card, thus abnormal conditions due to the high current of the machine card interface are avoided, and the power consumption is reduced at the same time, the standby time of the device which the smart card is in is improved.