Mobile Ad-hoc Network (Manet) consists of a set of network nodes which change, not based on an existing network infrastructure as well as the centralized control. Network nodes usually have limited energy, bandwidth limitations, so find a way to transfer packets in the network is very important. To minimize packet loss, efficient bandwidth utilization at the node requires routing protocol must be compact, efficient, accurate. Fuzzy logic is a logical field studies evaluating the accuracy of the results based on the approximation of the components involved, make decisions based on many factors relative accuracy based on experimental or mathematical proof. Each component of the logical expression is usually belong to one set of defined unclear (fuzzy set). In this paper, We give some researchs applied fuzzy logic in assessing the network routing and bandwidth management on the basis of a number of existing studies.