Structural optimization for radiation noise control of a simply supported plate is carried out using the time domain radiation modes. Recent study shows that these radiation modes in the time domain can radiate sound power individually, and the first order radiation mode is the dominant one. Based on these findings the design of Active Structureal Acoustic Control system is presented to cancel the first radiation modes amplitude by filter xLMS algorithm. And the optimization of arrangement of controlling force sources is analyzed and discussed. Finally, the validity of the proposed method is verified by a numerical example.