Model checking has long been used as a means of verification of formal specifications. This is a verification technique of dynamic systems that explores all possible states of the system. It determines whether the given system satisfies its specification. This technique suffers from the state explosion problem when traversing all possible states of systems. Parallel and/or distributed approaches are used to cope with the state space explosion problem. In this article, we propose a synchronized parallel algorithm of exploration based on a fixed number of threads. We present many experiments for a comparison between our parallel approach and the algorithm proposed for a parallel exploration in SPIN. We show by an experimental study that our parallel approach gives encouraging results.