The invention provides an update method for a mapping table, a control circuit unit of a memory and a storage device of the memory. The method comprises the steps that mapping table storage space is distributed in the buffer memory so as to store a physical address-logic address mapping table; whether residual storage space of the mapping table storage space is smaller than a threshold value is judged, wherein if the residual storage space is smaller than the threshold value, mapping information of the physical address-logic address mapping table stored in the mapping table storage space will be updated to at least one logic address-physical address mapping table, and the mapping information of the physical address-logic address mapping table stored in the mapping table storage space will be eliminated; and update mapping information of a corresponding programmed actuation physical erasing unit is stored in the mapping table storage space. According to the invention, the problem that programmed data cannot be recovered due to programming failures of other physical programming units after mapping table update can be avoided.