This paper carries out the health assessment of the civil aircraft hydraulic system. Based on the dissimilarity representation, one-class LP classifier is taken for the health assessment, to determine the parameters affecting the accuracy of the model assessment, to define the health index, to make the assessment of the overall test samples and non-normal samples, and to compare the results with the support vector machine hyper-sphere model. The evaluation results show that in the case of the selected appropriate parameters, one-class LP classifier based on the dissimilarity classifier model can assess the health of the civil aircraft hydraulic system, and performs better than the support vector machine hyper-sphere model.