Split phase storage technology is presented in recent years, using more physical storage resources to make system work at a higher speed. DDS adopts the technology tends to consume a lot of logical resources. This paper aiming at DDS splitphase storage technology resource depletion problems in practical application, analyzing difficulties in the practical application of this structure from the logic level, then puts forward a cascade splitphase phase accumulator structure to make up for splitphase storage technology in practical application. Taking the optimization to phase accumulator with four phase storage for example, comparing logic resources utilization ratio with and without optimization, the results proves that the optimized structure helps reduce 19.6% combinational logic resource overhead while has no effect on performance. Finally the optimized structure was successfully applied to 500MSPS waveform synthesis and proved its practical value.