Natural gas leakage pollutes the air,which is easy to cause explosion accidents and endanger personal safety.The long term leakage results in waste of resources.Therefore,natural gas leak monitoring has become an urgent problem to be solved in natural gas stations.Compared with other measurement principles,tunable laser diode absorption spectroscopy (TDLAS) technology has been widely used in natural gas leak monitoring in open environments due to its rapid response and non contact measurements.At present,natural gas stations generally adopt a multi point and multi line arrangement of multiple open laser gas telemeters for monitoring or use multiple scanning laser gas telemeters for cruise monitoring.These programs have small monitoring scopes and large loopholes.Based on the odd harmonic signal of TDLAS,the online reconstruction algorithm of recover absorption shape is established,and a space monitoring method and system for natural gas leakage is proposed.The system is based on a GIS platform to perform three dimensional modeling of natural gas stations.The monitoring data is fused and processed.The spatial concentration field inversion algorithm is used to obtain the concentration dynamic distribution map of the entire station after each dynamic scan.The test results show that the natural gas leakage monitoring has rapid response,high sensitivity and timely alarm linkage.In addition,the monitoring system also provides a clear three dimensional scene and a concentration dynamic distribution map with the leakage points accurately observed.