A memory system, a reading method and a writing method are provided. The memory system includes a memory controller and a memory array electrically connected to the memory controller. A parity information is stored in the memory array. The memory array includes a plurality of memory devices. The reading method comprises the following steps: A reading command for requesting a user data stored in the memory array is received from a host interface. The user data is recovered according to the parity information when the user data is error at one of the memory devices. The user data, which is recovered, is transferred to the host interface and the user data is refreshed.