Abstract: The article discusses variable quantity calculation method of such parameters as earth’s area,volume and radius in the earth expansion stage.The means that how to evaluate numerical val-ue of the earth expansion by actual data explains and lines up relative calculating formulae.On the basis of former research,the viewpoint about expansion stage,volume expanding stage,
magma filling amount continuous enlargement stage,magma fill-ing amount continuous diminishment stage, earth contraction stage and so on.The earth expansion process is not continuously enlargement and monotonously diminishment.It is controlled by periodic function force.The earth radius is growing slowly in re-cycling of enlargement-diminishment-enlargement-diminish-ment.

Key words: earth, expansion, variable quantity, monotony, recycling, algorithm