A memory device and an operation method thereof are provided. The memory device includes memory cells, each having a static random access memory (SRAM) cell and a non-volatile memory cell. The SRAM cell is configured to store complementary data at first and second storage nodes. The non-volatile memory cell is configured to replicate and retain the complementary data before the SRAM cell loses power supply, and to rewrite the replicated data to the first and second storage nodes of the SRAM cell after the power supply of the SRAM cell is restored.