1. A method of reading memory cells of a flash memory device, comprising: classifying memory cells in the flash memory device into at least two groups; detecting and latching data stored in of the selected memory cells corresponding to one of the at least two memory cell groups according to a first read operation; detecting and latching data of memory cells corresponding to another of the at least two groups according to a second read operation; and processing the data detected and latched according to the first read operation through a soft decision algorithm during the process of detecting and latching of the data according to the second read operation.