Green construction ecosystem was studied. The author analyses the system of construction, and proposed the system of green construction based on ecology theory which was included subsystem of the condition, process and objective on the ecosystem in order to lay the foundation for system evaluation. The text analyses elements of green construction system, which would help to improve the competitiveness of green construction for construction enterprises, and meet the requirements of environmentally friendly, resource-saving society. The competitiveness of green construction was considered with objective which was evaluated to maximize the competitiveness, and it overcomes the current competitiveness evaluation from the owners and the interests of construction enterprises ignoring the ecological environment. It is a new method which could provide a strong support as a business strategy based on ecological environmental protection, development and green construction program formulation. Analyses indicators of competitiveness and the relationship of the construction phase, it could identify the main reason for the green effect, and find the need to improve measures in order to lay the foundation for further enhancing the competitiveness of construction enterprises.