Abstract: The invention provides a cross-region access method for an embedded file system (EFS) including: step a. defining a critical resource region in a BANK which is shared by program codes and an EFS; step b. judging the type of an operation instruction, if it is a reading or writing operation instruction, utilizing the critical resource region to execute a time-division asynchronous operation to an FLASH, if it is a data erasing operation instruction, putting the instruction into a real-time operation system for management without affecting normal operations of other application programs. The invention introduces a new distribution mechanism for EFS space and performs time-division asynchronous operation by defining the critical resource region and a task machine; it avoids considering the limit of the bank boundary of the storage to the EFS space partition, utilizes the idle space of the storage sufficiently and reduces the cost.