In order to make up for the shortcomings of limited information that can be detected by a single low-field nuclear magnetic resonance analyzer or a single near-infrared spectroscopy instrument,and the cumbersome and time- consuming separation of sampling operations,by studying the transmission optical fiber used in near-infrared and low- field nuclear magnetic resonance with a main frequency of 21 M and acoil diameter with a combination of 25 mm probes, a joint analyzer capable of co-location and synchronous sampling to achieve complementary information has been developed.The performance test results show that the length of the low-field NMR homogeneous region is greater than 25 mm,the standard deviation of the near-infrared spectrum is less than 0.003,and other test results meet the application technical requirements.Finally,84 diesel samples were sampled and analyzed on the combined instrument, and the model was established based on the 50%recovery temperature and density of diesel.The results showed that the detection models based on feature extraction and data fusion were better than those based on low-field NMR and one detection model for a near-infrared single dataset.It can be seen that the combined instrument has a trend of information complementation in the analysis of diesel oil,and has practical application significance and promotion value in the detection fields of petroleum products,food agriculture,and biomedicine.