Recently there has been great significance attached to rubber lubricants because they are associated with high output, good product quality and low energy consumption. However, existing methods for characterising lubricating property are too apparent. According to a rheological method based on the Rabinowitsch equation and capillary wail slip correction, the ‘slip coefficient–β’ and ‘slip velotity–Vs’ at the metal wall can be determined. Therefore it is possible to characterise quantitatively the external lubricating property of various rubber lubricants with β and Vs.