Working memory is widely considered to be a necessary component of various cognitive operations. Many human cognitive abilities can be predicted by working memory capacity. However, it is still unclear whether it can predict the ability of evaluating emotional information. Here we investigated the relationship between working memory capacity and emotion evaluation using the measurement of event-related potentials. Two groups of college students with high and low working memory capacity were picked out using a 2-back task. They were asked to evaluate negative pictures preceded by negative or neutral meanings. We found that high working memory capacity group was more successful in adopting a neutral meaning to evaluate negative picture and showed decreased amplitude of electrocortical response. The finding supported that working memory capacity can predict the ability of emotion evaluation.