A method and a device for accessing a cache memory are provided. The method comprises: generating, by a bit prediction unit (BPU), a prediction bit corresponding to an instruction instructing to access the cache memory from a central processing unit (CPU); generating, by an instruction execution unit (IEU), a virtual address corresponding to the instruction; generating, by a load/store unit (LSU),a predicted cache index according to the prediction bit and a part of a virtual page offset of the virtual address; and reading, by the LSU, data from the cache memory by using the predicted cache index. Therefore, the maximum size of the cache memory could be increased.