NAND flash memory with fast programming function

A NAND flash memory, comprising:

• a plurality of levels of cells;
• a plurality of bitlines, wherein each bitline corresponds to a plurality of program states, the program states include an Erase-state, a highest state and a plurality of middle states, wherein bitline voltages of the middle states during programming are between a bitline voltage of the Erase-state and a bitline voltage of the highest state during programming, and the bitline voltages of the middle states during programming are different from each other;
• wherein the NAND flash memory is a multi-level cell (MLC) flash memory, and the bitline voltage of the highest state during programming is 0 volt;
• wherein the plurality of middle states include an A-state and a B-state, the bitline voltage of the A-state during programming is calculated by the formula
• VBL=DVA*program loop;
• wherein DVA and program loop are parameters preset in factory test.