Abstract: There is a certain internal relation between chemical equilibrium and ecological equilibrium. Similar dynamic characteristies have been found.The principle of chemical equilibrium is of universal guiding signficance for the limitation of chemical change and the realization of direction and of material transformation favorable to man. The shift law of ecological equilibrium and the direction control of its development can be well explained by using Le Chatelier’s principle. The quantitative concept of ecological equilibrium constant may arise from the analogy of the expression of chemical equilibrium constant and thus what ecological equilibrium is will be more scientifically understood.