The embodiment of invention provides a method and device for simulating a slow memory disk. The method comprises the steps of intercepting input/output I/O directives which are to be stored in a memory disk; based on a pre-determined delayed injection strategy assigning injection delays to obtained I/O directive to use the memory disk to simulate the slow memory disk. Based on all the execution modes of the method and device, cost of testing a slow disk is reduced, and the method and device are flexible and expandable.