Mobile ad hoc networks have consisted of the nodes which are freely displaced. In other words, this network has dynamic topology. Routing protocols find route of forwarding data packets from the source node to the destination node. A routing protocol plays important role in finding the shortest time and the route path. In this paper, considering significance of the subject, attempt has been made to present a model using fuzzy logic approach to evaluate and compare two routing protocols i.e. AODV DSDV using effective factor of the number of nodes based on 2 outputs of delay and throughput rate (totally fuzzy system with four outputs) in order to select one of these two routing protocols properly under different conditions and based on need and goal. To show efficiency and truth of fuzzy system, two protocols have been evaluated completely equally using NS-2 simulator and attempt has been made to prove efficiency of the designed fuzzy system by comparing results of simulation of fuzzy system and NS-2 software.