Abstract: The Triassic Baikouquan formation in the Mahu sag of Junggar basin are characterized by complex lithology and large variations of electrical parameters. Conventional logging methods can’t be used to effectively identify fluid properties in low permeability conglomerate reservoirs. NMR experiments show that T2 spectrum of water saturated rock sample is distributed ahead of the lateral relaxation time of 100 ms, but the actual NMR T2 spectrum of the layer at the corresponding depth is still distributed behind the lateral relaxation time of 100 ms, which reflects the signal of oil. According to the shape of the T2 spectrum and taking the lateral relaxation time of 100 ms as the marker to identify oil and water, sensitivity parameters and fluid identification chart are established. The result of fluid property identification in the reservoir of the study area by using the NMR method is consistent with the result of formation test, and good application effects has been gained during production.