A multi-angle spatial compound imaging method was developed to suppress the speckles and artifacts in ultrasonic immersion testing using a single transducer. The multi-angle echo signals were acquired by an ultrasonic immersion testing system with different incident angles. With consideration of the acoustic difference between water and the specimen, the deviation of the time of flight (TOF) and refraction were corrected. Then the corrected signals were superimposed to reconstruct a multi-angle spatial compound image. The performance of the proposed method is assessed with quantitative accuracy, signal to noise ratio (SNR) and contrast to noise ratio (CNR). Compared with the conventional B-scan imaging, the quantitative accuracy of the longitudinal and lateral sizes of the defect holes in proposed method are respectively improved by an average of 12.3% and 15.8%, and the SNR and CNR are increased by an average of 6.13 dB and 2.65 dB, respectively. The results show the advantage of the proposed multi-angle spatial compound imaging for ultrasonic immersion testing in terms of the less quantitative error and artifacts.