Abstract: In order to address the issue of that weakly defects are displayed in ultrasonic total focusing imaging after denoising, phase-coherent imaging (PCI), dB amplitude enhancement (dB) and total focusing algorithm (TFM) are combined in this paper. This combination improves image accuracy and enhances the distinguishability of defects. A carbon steel block with hole defects at different positions is modeled using COMSOL finite element software, with which the effects of various probe parameters on total focusing (TFM) imaging, total focusing-phase coherent imaging (TFM-PCI), and total focusing-phase coherent-dB amplitude-enhanced imaging (TFM-PCI-dB) is studied. Denoising and artifact removal are evaluated for TFM-mean denoising, total focus-dB amplitude-enhanced (TFM-dB), TMF-PCI, and TFM-PCI-dB imaging. The results indicate that: higher frequency probes yield greater imaging accuracy and more detailed information for both TFM and phase coherent imaging; array element spacing has minimal impact on accuracy ; increasing the number of array elements and their spacing expands probe coverage, resulting in more comprehensive image information. Among these methods, TFM-PCI-dB is demonstrated superior noise reduction capabilities while enhancing defect visibility, leading to higher image accuracy. Simulation and experimental results indicate that the TFM-PCI-dB method improves the detection accuracy and provides ideas for the field of high-precision defect detection.