The invention discloses a read-only memory which comprises a storage array, multiple bit output modules and a central control logic circuit. Each bit output module is a check bit output module or a non-check bit output module. The central control logic circuit is provided with check bit module control signals. The check bit module control signals are input to the check bit output modules, and values of the check bit module control signals are set according to the judgment whether check bits need to be output or not; when the read-only memory is in the working mode, the non-check bit output modules are in the working mode; when the read-only memory needs to output check bit data, the check bit control signals enable the check bit output modules to be in the working mode; when the read-only memory does not need to output check bit data, the check bit control signals enable the check bit output modules to be in the standby mode. The invention further discloses a data reading method of the read-only memory. The read-only memory can lower power consumption.