Abstract: A extrapolation model of isothermal compressibility of oxygen-free high conductivity copper is established,which is applicable in the temperature range of 5~300 K.Three sets of isothermal compressibility extrapolation models are established based on the data of room temperature (260~280 K), low temperature (140~160 K) and extremely low temperature (10~30 K) using this model.The extrapolation accuracy of each model is better than that of the literature model under the corresponding conditions.The average absolute relative deviations of three sets of calculation models are 0.199%,0.074%and 3.014%respectively.The extrapolation accuracy of the model in low temperature zone is the highest.The relative deviation of the isothermal compressibility coefficient of oxygen-free high conductivity copper from 5 K to 25 K is within 0.060%,and AARD is 0.048%,which can meet the requirements of the calculation accuracy of isothermal compressibility coefficient of oxygen-free high conductivity copper in this temperature zone.