High-resolution submarine seismic survey techniques have become necessary in many actual geological and geophysical investigations. A new type of mini-distributed acoustic sensing (DAS) module is developed for working at the bottom of the sea with several kilometers long single-mode fiber cable for tens of thousands of channels at the same time. Integrated designs of optics and electrics help to significantly reduce volume and power consumption. Compared with a common land-based DAS system, the size and power consumption of the mini-DAS module are significantly optimized. The size is 150  ×  300  ×  110  mm³ (width  ×  depth  ×  height), and the power consumption is down to 25 W. The spatial sampling resolution of ∼0.8  m is retained for high-resolution seismic profile in the deep sea survey. The upper limit of response frequency is set by 500 Hz for the channel sample rate of 1  kS  /  s to realize the long-term data storage. It presents a powerful signal acquisition ability with the average system noise of 4.79  ×  10^−  4  rad  /  √Hz and the minimum detectable strain is 10.4  pε  /  √Hz. The innovative mini-DAS module has high enough capabilities for real-time seismic wave signal detection in deep sea.