An evaluation method for the component importance of pin-jointed structures based on the redundancy theory was proposed. On the basis of the uniformity of the element-redundancy, the quotient of the standard deviation and the mean value of the element-redundancy was defined as the redundancy distribution index. The component importance of pin-jointed structures was evaluated by the redundancy distribution indexes of the remaining structures in the cases with different component removals. The redundancy distribution indexes of the remaining structures were defined as the component importance indexes. Three practical examples were given for illustration. The results showed that the redundancy distribution index can reflect the uniformity of the element-redundancy, and the proposed method is able to effectively evaluate the component importance of pin-jointed structures. The smaller the redundancy distribution index is, the more uniform the structural redundancy distribution is, which indicates better structural robustness. The higher the component importance index is, the greater the impact of corresponding member on the structural robustness is.