Abstract: The quasi-geostrophic atmospheric and oceanic equations of momentum and thermodynamics with dissipation factors are used to create a simple coupled ocean-atmosphere model describing the large scale shallow water motion. The ocean-atmosphere coupling effects are discussed separately for mid-high and low latitueds and variational characteristics are analyzed of oscillatory periods and coupled low-frequency modes (oceanic) against the coupled frequency and latitudinal number, on the basis of which the low-frequency oscillation is shown to be related to ocean-atmospere interactions. Then, from the dispersion curves of atmosphere and ocean, effects of the coupling strength on the propagation of Rossby waves are revealed. The conversion mechanism between the two modes is also discussed as viewed from the wave train that varies slowly.The results show that Newtonian cooling and Rayleigh friction stabilize oceanic Rossby waves and with growing coupled frequency, the period of coupled low-frequency mode increases and more rapidly so with .greater latitudinal number. When the coupling frequency approaches to a critical value, the oceanic Rossby Waves tend to be static. As the ocean-atmosphere coupling strength grows to some degree, the propagation of oceanic Rossby waves will reverse to its own opposite direction. One part of the oceanic Rossby waves is converted into atmospheric Rossby waves and the energy conversion coefficitnt is also derived in this paper.