A software defined binaural hearing aid system with a smartphone-centered architecture has been developed. This architecture takes advantage of the powerful computing hardware and memory capacity of smartphones. The sound signals are captured under complex acoustics scenes. And they need further enhancement to satisfy patients' personalized requirements. A minimum variance distortion response (MVDR) and binaural multichannel wiener filtering (MWF) combined algorithm (MMC) for speech enhancement is proposed. The proposed algorithm can achieve balance between noise reduction in complex acoustics environment and preservation of interaural cues therefore improve speech intelligence at the same time. The subjective and objective evaluation results as well as running on the binaural hearing aid with smartphone platform case demonstrate the efficiency of our work.