In order to get reliable results,the measurement parameters of low field NMR(LF-NMR) should be optimized.In this paper,effects of instrument parameter,temperature and volume of the sample on the stability and reproducibility of the results were investigated,by using soybean oil as the object.The results indicated that good stability and reproducibility can be guaranteed if the following parameters such as TR=2 000 ms,τ=200 μs,EchoCount=5 000,NS=4,TD=500 050 and SW=250 kHz are chosen.Before the measurement,a sample of 2.5 mL should be stabilized at 32 ℃ for 10 min,and subsequently transferred to the probe and tested after 1 min stabilization.The results can provide appropriate detection conditions for the latter application of LF-NMR technique in the determination of oil quality.