A catastrophe theory based power grid blackout traffic jam degree evaluation method comprises the steps of using basic road sections as starting points, selecting an evaluation index, performing step-by-step upward calculation according to a catastrophe mode and data of bottom-layer index to obtain the jam degree of each basic road section after blackout, and adopting vehicle travel miles as a weight to conduct weighting on the basic road sections so as to obtain the traffic jam degree of a weighted road network. The catastrophe theory based power grid blackout traffic jam degree evaluation method adopts a catastrophe series evaluation method to conduct quantitative evaluation on the traffic jam degree of the road network after blackout and overcomes the shortcoming of high subjectivity of the evaluation index weight allocation and index quantification aspects. By means of the catastrophe theory based power grid blackout traffic jam degree evaluation method, an evaluation value of the traffic jam degree of the road network after blackout can be obtained through calculation, corresponding jam level situation is obtained according to grading standards, and therefore, the transportation agency can evaluate the severe jam degree of the road network and take a corresponding emergency measure.