Abstract: A simple coupled earth-ocean-atmosphere linear model has been built. It includes angular momentum conservative relation between the solid earth and the atmosphere, the effect of frictional force from the earth spin’s variation on atmosphere, wind stress on ocean and SST anomalies leading to redistribution of atmospheric mass. Without the external forcing, the result of the model shows that there is a quasi-biennial oscillation (such as zonal wind, SST and the earth spin’s rate) occurred in every part of the earth system. Accordingly, the quasi-biennial oscillation is an inherent oscillation occurred in the interior of earth system