Western mainstream economic growth theory is not as obviously successful in the guidance of the economic development of the developing countries as in the guidance of the developed countries, and the middle-income countries are ubiquitously bogged down in middle-income trap. The typical middle-income countries rapidly realized industrialization by depending on externally pouring in during the economic taking-off stage, however, because those countries did not cultivate the national enterprise system and mature local capital market with self-growth capability, their national economy has such three types of leaking as international leaking, government leaking and oligarchy leaking, no matter externally pouring in or internally pouring in it is offset by the three types of leaking and boosts its ineffectiveness of the economic growth policy provided by western economic growth theory.. The key to stopping the economic cycle leak of the middle-income countries is to cultivate healthy national enterprises, to construct and maintain local capital market and to build healthy economic body. From long-term perspective, the breakthrough of middle-income trap needs triple coordinated development of government-market-society, and the hydrodynamics and the pouring in and leaking out mechanism of national economic cycle also provide new vision for the innovation and development of economic growth theory.