As code reuse attacks (CRA) are becoming increasingly complex, legacy code randomization methods have been unable to provide adequate protection. An approach called LCR is present to defense CRA by living code randomization. LCR real-time monitors all suspicious operations which aim to find or utilize gadgets. When above events occur, LCR randomizes the function blocks of the target process in the memory so that gadgets' information known by attackers become invalid and attacks composed of these gadgets will fail. Finally, a prototype system of LCR is implemented to test the proposed method. Experiment results show that LCR can effectively defense CRAs based on direct or indirect memory disclosure, meanwhile introduces low run-time performance overhead on SPEC CPU2006 with less than 5% on average.