The perovskite-type nanocrystal LaMnO3 was prepared using sol-gel auto-combustion method with citric acid as the chelating agent. Some analytical methods consisted of FT-IR, XRD, TEM and wave-guide method were used to characterize the gel and the final products. The metal ions coordination compound, obtained from nitrate and citrate, underwent an auto-combustion process and voluminous ashes formed when calcining the complex in the air. From the result of the dielectric properity. It was shown that the dielectric coefficient curves and dielectric loss curve of LaMnO3 nanocrystals were smooth in the range of 8-11MHz. The dielectric loss can be obversed obviously in the measured range.