Memory system having multl level cell flash memory and programming method thereof

A memory system having a multi level cell flash memory and a programming method thereof are provided to improve data integrity of control data by comprising a cache block programming only least significant bits. According to a programming method of a multi level cell flash memory, a user block and a cache block are classified in a memory cell array of the flash memory. First least significant bit data is programmed in a page of the user block. First most significant bit data is programmed in a page of the user block. Second least significant bit data is programmed in a page of the cache block(S150). The cache block stores control data required to control the flash memory.