The invention provides a memorizer partition isolating method and device and an electronic device. The method includes the steps of before read-write operation is conducted on the designated logic block address of an external storage device, establishing a read-write operation command containing a designated logic block address, judging whether the read-write operation command has execute permission or not, and correspondingly processing the read-write command according to the result of judgment on whether the read-write operation command has execute permission or not. The access of software to an unauthorized logic block address can be stopped under a limited scene, the read-write and damage of malicious software to secure data are effectively avoided, and the influences on system performance are small.