Abstract: For memristor-based full adder, the output result of pre-structure is necessary to be transferred to the post-structure, which is stored in the form of resistance value and cannot be utilized directly by the post-structure. Targeting at this problem, a novel read-out structure is proposed which converts the value of memristor resistance into voltage value. Based on the proposed structure, a memristor based full adder has been improved and based on this memristor based multiplier is designed and bit-width can be freely expanded. By two-bit multiplier example, based on HP memristor model and by LTspice simulation, it is demonstrated that the proposed structure can efficiently support bit-width expandation of memristor based multiplier.