In this paper, dynamics and complexity of the integer-order and fractional-order centrifugal flywheel governor systems are investigated numerically by the bifurcation diagram, Lyapunov exponents (LCEs), chaos diagram and spectral entropy (SE) algorithm separately. Moreover, the effect of periodic force and stochastic noise on the dynamics and complexity of the integer-order and fractional-order systems also are analyzed. Finally, the multistability of the system is discussed by coexisting attractors and the basins of attraction. The results show that the fractional-order system has rich dynamical behaviours. Stochastic noise has a great effect on dynamics and complexity of the integer-order and fractional-order systems. The high complexity region is determined and SE complexity can indicate different state of the system effectively. And the integer-order and fractional-order systems show multistability with the variation of initial conditions. INDEX TERMS The centrifugal flywheel governor system, fractional calculus, multistability, stochastic noise, coexisting attractors.