The purpose of extracting evaluation object of the microblog involved in a case is to identify the case object terms of the user evaluation from the microblog comments， which helps to grasp public thought on different aspects of a certain case. In general， the existing methods regard evaluation object extraction as a sequence labeling task， but do not take into account the domain characteristics of the microblog involved in the case， that is， comments are usually discussed around the case keywords that appear in the microblog text. For this reason， this paper proposes a sequence labeling model based on case keyword structured encoding to extract the evaluation objects of the microblog involved in the case. First of all， a number of case keywords are obtained from the text of microblogs， and the structured encoding mechanism is used to convert them into keyword structural representations. After that， the representations are integrated into the comment sentence representation through the cross attention mechanism. In the end， the evaluation target terms are extracted by the conditional random field （CRF）. Experiments are conducted on the data sets of two cases. Compared with the multiple baselines， the encouraging progress validates the effectiveness of the proposed approach.