A compact room-temperature inter-digital H-mode (IH) drift tube linac (DTL) with Kombinierte Null Grad Struktur beam dynamics is proposed in this paper. The proposed IH-DTL, which operates at 325 MHz, accelerates 18 mA proton particles from 3.0 to 7.0 MeV as part of a proton synchrotron-based therapy system. It is composed of two main sections, namely a bunching section (- 30°) and accelerating section (0°). There is no trans-verse focusing element inside the cavity, which increases the acceleration gradient and reduces the cavity length and power consumption. In our physical designs, LORASR code is utilized for beam dynamics design and multi-par-ticle simulations. The synchronous particle energy, injec-tion phase, and acceleration voltage of each gap are optimized carefully to increase transmission efficiency while minimizing beam emittance growth and beam loss. The total length of the cavity is 0.82 m and the acceleration gradient reaches 4.88 MV/m, resulting in a transmission efficiency of 100％ and beam emittance growth less than 10％. The details of the specific work undertaken in this study are presented in this paper.