Transmission principle is the base of design theory research. The work proposed a new type of swing oscillating gear transmission—swing oscillating gear transmission of shockwave isometric polygonal profile. This transmission was convenient for optimization with simple design method, which could implement transmission of arbitrary tooth difference. The basic structure and transmission principle of this oscillating gear transmission were introduced with analysis on the main character. The transmission was proved as the one with constant transmission ratio. Based on ways of installation and the number of oscillating gear, twelve transmission ratios can be obtained to derive theory and actual tooth profile equations of shockwave gear and inner gear. Meanwhile, design conditions were proposed to avoid tooth interference of central gear. Therefore, MATLAB program was used to imitate the tooth profile based on the design of this type of transmission.