High-speed high-multiplexing distributed temperature sensor network based on weak-reflection fiber gratings is proposed. In order to solve problems such as long monitoring time and poor real-time performance of the system, a multiple-wavelength light source is used instead of tunable laser. Three fiber Bragg gratings (FBG) with high reflectivity and low bandwidth are carved on a single fiber and their central wavelengths are 1529.488, 1545.202 and 1557.100 nm, respectively. Another three groups of nine FBG whose central wavelengths are 1529.488, 1545.202 and 1557.100 nm with 3% reflectivity are carved equidistantly on the same fiber. Light from the high-reflection FBG is used as the light source of the system and the weak gratings are used as the monitoring gratings. The experimental results show that, in the temperature range of 5 ℃~80 ℃, the central wavelength of each weak-reflection FBG changes linearly as the temperature changes, and the error of temperature measurement is ±0.5 ℃ and spatial resolving power is 10 m.