Abstract: A NAND flash controlling method includes the steps of: configuring a temperature-sensing unit to detect the flash temperatures and a source block to store source data; configuring a main control unit to receive the flash temperatures for calculating a temperature difference, to generate a data-transmitting signal if the current temperature is abnormal and the temperature difference is too large; configuring a control unit to read and transmit the source data; configuring a data-buffering unit to receive and store the source data; configuring an error-correcting unit to receive a source error-correcting code and a source bit-error rate to re-calculate an updated error-correcting code; configuring a flash-buffering unit to receive the updated error-correcting code and the source data; and, configuring the control unit to utilize the updated error-correcting code to write the source data into the destination block from the flash-buffering unit. In addition, a NAND flash controlling system is also provided.