The invention discloses a capacitance type oilpaper transformer sleeve insulation state assessment method, which belongs to the electrical equipment insulation diagnosis technology field, relates to the capacitance type oilpaper sheathed tube insulation diagnosis and particularly relates to a capacitance type oilpaper sleeve insulation state assessment method. The capacitance type oilpaper transformer sleeve insulation state assessment method comprises steps of performing the mathematics exponential function fitting on the cannula capacitance frequency domain spectrum curve through the combination of the mathematics modeling simulation and laboratory test and utilizing the integration of the fitting function to perform description on the frequency domain spectrum curve variation under various insulation states. As a result, the accurate and lossless assessment on the cannula insulation state through the application of the frequency domain dielectric spectrum method can be achieved. The capacitance oilpaper transformer sleeve insulation state assessment method can perform accurate assessment on the insulation state without assembling and disassembling the cannula, and is easy. Furthermore, the capacitance oilpaper transformer sleeve pipe insulation state assessment method can make accurate and effective assessment on the insulation state of the capacitanc type oilpaper cannula and can provide accurate basis to the maintenance and replacement of the cannula.