Abstract: Towed line array sonar （TLAS） has been playing an important role in anti-submarine warfare. The principle, characteristics and configurations of TLAS are briefly introduced. The history of TLAS from the inspiration of H. C. during World War I to the ‘thin array’ of J. R. Potter in 2000 is reviewed, and it is predicted that future TLAS will be composed of passive and active modulated multiple arrays with fiber-optic hydrophones and new acoustic sources, and will be capable of locating targets in 3-dimensions.