Data writing and reading methods for a flash. The data writing method comprises: when remaining spaces of a data area and of an index area of a physical page are sufficient, sequentially storing present-instance write data into the data area of the physical page, and generating an index journal and sequentially writing same into the index area of the physical page; otherwise, organizing actual data in the physical page, storing the actual data into a data area of an idle page, and generating, on the basis of the actual data, an index journal and writing same into an index area of the idle page. The data reading method comprises: acquiring the actual memory address of to-be-read data on the basis of the index journal in the index area of the physical page, and reading the data from the actual memory address.