To insure the credibility of large-scale complex system simulation, it is very significant to study verification, validation and accreditation in modeling and simulation of the whole life cycle. The VV&A methodology and principle for LCSS are represented by theoretic research. Taking the case of HLS dimulatopm for example, the VV&A process is studied at three levels, the simulation component, federate and federation levels. The research is applied in the anti-ship missile's penetration federation. The practice shows that this research will give good guidance to the VV&A job for LCSS, which will ensure the credibility of simulation.