This study investigates pipeline defect imaging using ultrasonic guided waves based on a sparse-array total focusing method (TFM) integrated with a phase coherence factor (PCF). Conventional TFM suffers from significant limitations, including excessive fullmatrix data volume, prolonged imaging processing time, and relatively low signal-to-noise ratio (SNR), which hinder the effectiveness of pipeline nondestructive testing. To address these issues, this research proposes an optimized TFM method by employing a sparse-array configuration, reducing the number of transducer elements from 32 to 8 while maintaining sufficient acoustic coverage, thereby decreasing the data volume by a factor of 16. Furthermore, to ensure imaging quality with the reduced array, a phase coherence factor (PCF) is introduced to suppress noise interference by leveraging the phase consistency of echo signals, significantly improving computational efficiency without compromising imaging resolution. Compared with conventional 32-element TFM, experimental results show that the proposed method achieves an approximately 120% improvement in SNR and a 38% enhancement in imaging efficiency, effectively reducing processing time while improving detection performance. For scenarios involving multiple coexisting defects, this study develops a multi-defect superposition imaging technique based on the TFM-PCF data matrix. By utilizing the phase coherence characteristics of defect signals, this method enables phase-synchronized enhancement of multiple defects, improving both SNR and detection rates. Specifically, the proposed method increases the SNR for double-hole defects from 32.97 dB (conventional TFM-PCF) to 42.69 dB, representing a 30% improvement. The reliability and effectiveness of this method are experimentally validated for various pipeline defect conditions, demonstrating its potential for practical industrial applications in high-precision pipeline inspection.