Dynamic binary translation technology allows a program written for one architecture to be executed on a second architecture without recompiling the source code. Effective dynamic binary translation of SIMD (Single Instruction Multiple Data) instructions has become more and more important as SIMD extensions have gained popularity among general-purpose CPUs within the last decade. Many SIMD extensions allow an SIMD1 register to hold data of different types at different times. Supporting multiple data types within the same register complicates the task of a dynamic translator, which may or may not be able to determine the type of the register at translation time. We propose the SIMD data type tracking algorithm to translate the SIMD instructions and three algorithms to further optimize the translation. Our results show that the three optimizing algorithms give overall 3.89% performance improvement for SPEC2K INT benchmarks and 6.61% for SPEC2K FP benchmarks.