In order to measure the ozone concentration， a 3.3 μm laser heterodyne spectrometer for field observation was built and the spectral resolution was measured to be 0.004 cm^-1. The ozone spectrum was measured at Golmud in Qinghai Province by the 3.3 μm laser heterodyne spectrometer， and the ozone concentration was inversed by using the optimal estimation algorithm. During the field observation， the average column concentration of ozone was inversed to be 241.7 DU， the column concentration increased about 4 DU/h. The results show that the laser heterodyne spectrometer combines with the optimal estimation algorithm is capable of measuring the ozone concentration of the whole atmosphere at the plateau， and has important applications for the environment， meteorology and laser atmospheric transmission assessment.