This paper proposes a long-distance sensing system using ultra-weak fiber Bragg grating arrays. By taking advantages of the discrete distribution and high signal-to-noise ratio of ultra-weak fiber Bragg gratings, this system employs a segmented acquisition method to decrease the requirements for data caching and computing capabilities. For spatial demodulation of the 10 km sensing section, ZYNQ (ZYNQ-7035 All Programmable SoC) embedded hardware is used. To design the input pulse power and Raman fiber amplifier configuration with power balance and dynamic segmented gain control, the OptiSystem software is employed to simulate and analyze the power budget of the system. An experimental system is constructed and validated, showing that the system's operating range can reach 50 km, the fluctuation of sensing signal intensity is less than 2.2 dB, the spatial resolution is 1.5 m, the demodulation speed is 0.3 Hz, the remote demodulation accuracy is within 6 pm, and the measurement accuracy for temperature and strain is ±0.15 ℃ and ±5.5 με, respectively. The overall system performance outperforms traditional Brillouin optical time-domain reflectometer and exhibits good scalability while demonstrating significant technical advantages in long-distance fiber temperature and strain sensing.