Existing distributed fiber-optic sensing systems often target only a single parameter, whereas in practice, when operating in complex environments, multiple sensing systems and technologies need to be integrated to monitor various parameters. Using the characteristics of phase-sensitive optical time-domain reflectometer (-OTDR) and Brillouin optical time-domain reflectometer (BOTDR), which are sensitive to different physical parameters, an integrated distributed fiber-optic sensing system was designed. By employing the concurrent detection of Rayleigh and Brillouin scattering signals, various parameters such as vibration, temperature, and strain can be effectively monitored using a singular sensing fiber under a unified modulation pulse. The system relies on the concurrent detection of Rayleigh and Brillouin scattering signals to enhance the spatial resolution of BOTDR while upholding the unaltered modulation of the integrated system pulse. The Brillouin scattering signal was analyzed based on the principle of pulse subdivision superposition, which breaks through the limitations of phonon lifetime and improves spatial resolution without changing the pulse width. The system was experimentally verified to achieve vibration localization with a spatial resolution of 10 m based on Rayleigh scattering at a sensing distance of 50 km. Introducing pulse subdivision superposition based on Brillouin scattering increased the spatial resolution to 1 m for detecting temperature and strain. The Brillouin frequency shifts displayed a highly linear correlation with the changes in temperature and strain, thereby realizing the monitoring of multiple covariates.