In order to extend sensing distance, we report a Brilouin optical time domain analyzer (BOTDA) based on distributed o ptical ampllification pumped by a random fiber laser (RFL).The novel concept of utilizing a random fiber laser (RFL) based on Rayleigth distributed feedback (DF B) to extend the sensing distance of fiber-optic system is proposed for the fir st time to our knowledge.BOTDA is a distributed optical fiber sensor based on si mulated Brillouin scattering,and it can monitor the temperature along the sensin g fiber.In this scheme,the sensing signal is distributedly a amplified by random fiber laser pump in order to extend the length of sensing and detect the temper ature along a long distance.The random laser is used as a sensing signal full di stributed second order pump,combined with coding technology.Random laser pump ha s low intensity noise compared with traditional Raman pump.At the same time,in t his design,random laser and the probe transmit in opposite directions which limi ts the RIN transferring.The experimental results indicate that a ±4m spatial r esolution has been achieved over a sensing distance of 100km.By calculating the standard deviation,the measurement precision is ±1.2℃ for 0－20km section ,±2.5℃ for 20－64km section and ±5℃ for the last section. .