The present application discloses a battery cell module and a battery system. The battery cell module includes a plurality of battery cell units, each of the battery cell units includes a battery cell and a base, and bases of adjacent ones of the battery cell units are detachably connected to each other; the base includes an installation slot and a pressure relief cavity communicated with each other, where an end of the battery cell is disposed in the installation slot, and the pressure relief cavity is provided with a plurality of pressure relief holes. Each battery cell is individually provided with the base, and the bases are spliced to form a group, which is beneficial to improve relative position accuracy between battery cells, thereby improving assembly accuracy of the battery cell module. The pressure relief cavity is communicated with the installation slot, which can make gas generated by the battery cell enter the pressure relief cavity under circumstance of thermal runaway and be discharged through the pressure relief holes to avoid burning or explosion of the battery cell. By adopting the above battery cell module, the battery system has high processing precision, low cost, and a reliable structure.