Talking about mooring systems for Wave Energy Converter shall be taken into account not only the station-keeping problem but also the influence of the mooring on the device motion. In literature several software for mooring modeling could be investigated, and among these software MoorDyn should be considered for its versatility. By the way, each model should be validated against experimental data to test its reliability hence, the aim of these paper is to follow the analysis which starts from an overview of the mooring system models and software and which ends with a model validation which has been performed against the experimental data obtained during Naples experimental campaign. Device kinematic has been recorded through a data acquisition system equipped in the scaled wave energy converter, and it has been used as input of the numerical simulation. The force recorded with a load cells system, connected with the mooring lines and the device, has been compared with the numerical one, derived from MoorDyn, and they have shown a marked overlapping that witnesses the validation.