A quasi-steady model describing aerodynamics of hovering Ruby-throated hummingbirds is presented to study extent of the low-order model in representing the flow physics of the bird and also to separately quantify the forces from the translational, rotational, and acceleration effects. Realistic wing kinematics are adopted and the model is calibrated against computational fluid dynamics （CFD） simulations of a cor- responding revolving-wing model. The results show that the quasi-steady model is able to predict overall lift production reasonably well but fails to capture detailed force oscillations. The downstroke-upstroke asymmetry is consistent with that in the previous CFD study. Further analysis shows that significant ro- tational force is nroduced during mid-stroke rather than win~ reversal.