The direct operating cost of aircraft is directly related to the design scheme and parameters of the aircraft，which is the main factor to be considered in aircraft economic design. Reliability and safety are the inherent attributes of aircraft and the prerequisite for ensuring safety in use. The parameterized design is regarded as an important factor which is restricting the efficiency-cost ratio of an aircraft. In order to improve the competitiveness of civil aircraft in the aviation market，a optimization model is constructed to consider reliability and safety simultaneously during the initial design stage from the view of system engineering. An integrated design idea of reliability and safety based on cost is proposed. The model is on the basis of connection of reliability，safety and cost，where the reliability and safety indexes being as the objective，and the plane cost and performance parameters being as constraints. Finally，an integrated design method of reliability and safety and its validation procedures are established based on the cost constraint，which provides technical support for the development of new generation large civil aircraft in China.