In this paper, the resonator performance of a small hammer structure with the interdigital end of the total aperture length on an Incredible High-performance surface acoustic wave (I.H.P. SAW) substrate is researched. On the substrate structure of Y42°-lithium tantalate (Y42°-LT)/SiO2/polysilicon (Poly-Si)/Si, the corresponding 3D finite element simulation model was established. It was preliminarily concluded that the increase of the total aperture length with the hammer structure can suppress the stray in the transverse modes. The layouts of a single port resonator with a total aperture length of 7.5, 10, 15, 20, 25, 32.5, and 40 times of the period at 1.44, 2, and 2.56 m periods are drawn and taped out. According to the measured results, it is concluded that with the continuous increase of the total aperture length in different periods, the suppression of the transverse mode of the resonator will continue to increase, the electromechanical coupling coefficient will also continue to increase, and the impedance ratio is the highest near the period with a total aperture length of 20 times. The above simulation and measurement results show that the total aperture length has a great influence on the performance of I.H.P. SAW resonator, which provides design guidance for high-performance resonators used in I.H.P. SAW filters.