This work experimentally investigated the effect of coupling on transverse vibration characteristics of a rotor system. Rigid and flexible couplings were used in the rotor system for investigating the relationship between the coupling and transverse natural frequencies of the system. An experimental test rig was set up to investigate the transverse vibration characteristics of the rotor system using the experimental modal analysis. It was demonstrated that the coupling type influenced the transverse fundamental frequency of the rotor system, and the use of more rigid coupling could increase its frequency and the associated critical speed. Using numerical modeling of the rotor system, an equivalent rotor system with particular boundary conditions was proposed for different coupling types. The numerical models for systems with/without coupling connected to the rotor were verified using experimental investigation. It was demonstrated that the effect of coupling on transverse vibration of the rotor system can be approximated using this equivalent model that can be used to assist the rotor design.