Abstract: Monthly OAM variability during 1985-2001 is estimated from a simple ocean data assimilation(SODA) analysis.The SODA analysis is near the global,spanning the latitude range 62°S~62°N.On the basis of the principle of angular momentum conservation in the whole Earth system including the solid Earth,atmosphere,ocean,hydrology,etc.,the residual between the solid Earth and geophysical fluids(atmosphere and hydrology) can be the constraint on OAM variability.And here the constraint are inferred from the Length-of-day change and polar wobble of the international earth rotation service(IERS),the atmospheric reanalysis of the national centers of environmental prediction(NCEP),and the hydrologic and 1-10 hpa atmospheric processes of a climate model output of Japan meteorological agency(JMA).Results indicate that at seasonal scale,the equatorial OAM variability and the constraint along the Greenwich meridian direction from 1985 to 2001 agree with each other significantly.