Load-independent output voltage (LIV) and zero input phase angle (ZPA) are the preferred operations of wireless inductive power transfer (IPT) systems to eliminate output regulators and to minimize voltage-ampere rating, respectively. Intuitive from the commonly-used T model of the loosely-coupled transformer, a conventional design concept is frequently adopted for the series/series-parallel (S/SP) compensated IPT system to achieve LIV and ZPA. However, it does not take efficiency optimization into consideration. In this paper, a novel design methodology of the S/SP IPT system is presented, which can help improving the efficiency performance, while maintaining LIV and ZPA simultaneously. Experimental results are presented to verify the proposed design methodology and the efficiency performance. Compared with the conventional compensation design, over 2.5% efficiency improvement is achieved.