Researches on simulation credibility are important in system simulation theory and application. As a hotspot in current Modeling and Simulation (M&S), Large-Scale Complex System (LSCS) has series of characteristics and puts forward some new requirements for credibility evaluation. Aiming at adapting to the new circumstance and figuring out the arisen issues, the dissertation researched into theoretics, process, techniques and tools of credibility evaluation for LSCS modeling and simulation from engineering and engagement level.Starting with some fundamental notions of LSCS modeling and simulation, the dissertation analyzed the principium of M&S based on similarity theory, discussed relations among system, simulation and evaluation. Then the qualitative and quantitative descriptions of credibility were given out, the relations between credibility and fidelity, between credibility evaluation and VV&A (Verification, Validation and Accreditation) were discriminated. And then the reference framework for credibility evaluation researches was built up, the connotation of the framework was illuminated and the application of it was expatiated. For a sound discription and representation of LSCS simulation credibility, concepts of credibility collection and relation were put forward, techniques for describing the collection were given out, some basal operators were defined, and the characters of the relation were analyzed; finally, the applications were illustrated by some representative models.Multi-Resolution Modeling (MRM) is one of the intrinsic attributes in LSCS modeling and simulation. After clarifying the connotation of model resolution, the dissertation analyzed two main factors influencing MRM credibility—precision and consistency. An approach for quantitative measure of model resolution was put forward based on LOD (Level of Detail) and DOD (Degree of Detail), the concept of DOC (Degree of Consistency) was given out and the measure and calculation of it were provided. Finally, a description and representation of MRM credibility based on precision and consistency was established, techniques and process for the evaluation were analyzed. The evaluation paradigm shows that the measure is simple and intuitional, and the result can offer explicit guidance for application.Credibility evaluation of LSCS simulation is a systematical and complicated job. The dissertation analyzed the intention of evaluation process researches and introduced some common process modeling techniques. Then the IDEF0 process model for credibility evaluation was built up from a high level view, and the formalization of it was given out. Evaluation Process Management (EPM) is the key factor in implementing credibility evaluation; the dissertation analyzed the static structure and the dynamic behavior of EPM from micro-realization viewpoint, and discussed the supporting environment in succession. The models and description not only offer support for process analyzing, reengineering and