Abstract: This article has a deep analysis on the potential danger of the Exclusive OR (XOR) and Hash chain based light weight Radio Frequency Edentification (RFID) security protocol brought by some articles. On the base of analysis, combining the traditional security schemes widely used in Internet or existing application systems and some light weight and resource-saving security mechanism, we enhance the lightweight RFID security protocol mentioning above and give a new light weight RFID security protocol. Special attention is focused on the deployment considerations for applying the protocol in real application to avoid the identified potential risk. Full consideration is given to the low cost demands for RFID tags, the power restrictions, and the non-resistant against physical tampering feature, which are common limitations in the RFID system.