The application relates to a description and evaluation method and device for a node voltage sag tolerance characteristic. After acquisition of a sag amplitude, duration, a starting point and phase hopping in a voltage sag event and dimensionless processing, an association matrix is generated for the data after the dimensionless processing; a quantitative index is formed with consideration of event influence weights of the sag amplitude, duration, starting point and phase hopping in the voltage sag event; and the severity of the node voltage sag can be evaluated conveniently based on the quantitative index.