A data writing method, a memory controlling circuit unit and a memory storage device are provided. The method includes: receiving a plurality of data; writing the plurality of data into a first physical erasing unit by using a multi-page programming mode; and writing at least one first data of the plurality of data into a second physical erasing unit by using a single-page programming mode; verifying the plurality of data stored in the first physical erasing unit; and if the verification fails, performing a writing operation to a third physical erasing unit by using the multi-page programming mode according to the at least one first data and the plurality of data.