Abstract: The effective distinction between oil and water in porousmedia is a difficult problem to solve in research on microscale remaining oil.Since a NMR relaxation time spectrum can accurately measure fluid saturation in porous media, we can apply it to this research by introducing a new parameter: diffusion coefficient, which can solve the problem of the quantitative distinction between oil and water.At the same time, the problem of the missing components in high viscous oil measurement has been completely solved through improving equipment, optimizing the calculation method and establishing the stimulated echo bipolar pulse gradient.As a result, the technology can fully meet the demand of microscale remaining oil research, which provides a new experimental technique for the quantitative characterization of this remaining oil.