Abstract: Abstract: As the carrier of underwater detection equipment, the positioning accuracy of deep towing system has a direct impact on data acquisition and reliability. In this paper, we discussed the key technical problems in underwater positioning for deep towing, and the underwater positioning methods suitable for deep towing system are summarized. Acoustic positioning technology, such as the ultra-short baseline positioning system, has the advantages of high stability and precision, and has thus become an important technical method for underwater positioning. Combined with field examples, this paper is devoted to the working principles, error analysis and data processing methods of ultra-short baseline positioning. With Kalman filter algorithm, the ultra-short baseline positioning data is processed, and the hopping points in the positioning data are filtered out, as the consequence of which the filtered data is getting smoother and well matches the original data.