Abstract: A new watermarking technique based on LUT replacement is proposed.Firstly,the watermarks are embedded into the memory logic array block(MLAB).Then,use a MLAB-based RAM to replace the corresponding LUT of original IP core.Because of the property of MLAB,the signatures embedded in MLAB can be preserved from the optimization process of EDA tools.The experimental results show that the method is more effective.The overheads and timing penalty of watermarking are very low,compare to other LUT-based watermarking technique.