Personnel competency assessment is the prerequisite and foundation for governments and enterprises to establish job requirements, select and appoint excellent talents, develop training plans, optimize talent structure, and promote development. Because personnel competency has potentiality, fuzziness, and dynamicity, and assessment experts have personal preferences, limited rationality, and experience limitations, it is very difficult to make objective and accurate assessment of key personnel's post competency. As a data fusion method for uncertain information, evidence theory fits the natural process of key personnel assessment. Therefore, in accordance with the natural practical process of key personnel competency assessment, this paper analyses the various types of data, information characteristics and evidence synthesis process in personnel competency assessment, takes into account the complexity and multi-stage nature of the assessment process, considers the limited rationality and preferences of the assessment experts, and puts forward a decision-making method of personnel competency assessment based on multi-stage and multi-source evidence fusion based on the evidence theory and the information of preferences, and conducts a case study on the evaluation of the title of a certain university as an example.