Abstract: Hybrid bunching-accelerating structure (HBaS) is a novel RF structure integrating a standing-wave(SW) pre-buncher (PB), a traveling-wave (TW) buncher (B) and a standard accelerating structure together. This paper presents the design results, including beam dynamic optimization, microwave design and the cold test of the S-band HBaS prototype, and explicates the reason of transverse emittance increasement caused by the hybrid structure. The low RF power results are in good agreement with the RF design. The measured S₁₁ at operation frequency is less than −45 dB, the phase shift deviation is less than ±2° and the bandwidth is more than 5 MHz (VSWR≤1.2). The axis field distribution fully meets the dynamic requirements.