Mechanical composite pipe with good corrosion resistance and economic performance has a broad application prospect.At present, the selection of composite pipe condition in gathering system shall consider the impact of operating temperature, pressure and medium on the cracking performance of lining chloride of high temperature resistance.In order to ensure the reliability of mechanical composite pipe, the basic pipe-lined tightness requirement is specified in the existing manufacturing specifications. During the real production, the pipeline running state is complex, but the current design specifications have not yet quantified to ensure the mechanical composite pipe tightness.To further ensure that the mechanical composite pipe is properly used in gathering system with high temperature and high pressure, it is necessary to further explore the mechanical composite pipe in the applicable conditions. Based on the theory and index of compactness of mechanical composite pipe at manufacturing stage, combined with the theory of steel pipe strength and natural anchorage law, the stress calculation formula of stainless steel lining under manufacturing and operation is deduced, and the tightness checking method is proposed. The results show that the axial compressive stress of the lining of the mechanical composite pipe is higher than the yield limit, which leads to the decrease of the tightness after the test. The axial compressive stress of the lining should not exceed the operating condition of collapse test; temperature difference between operation and installation and elastic laying are the main factors limiting the use of mechanical composite pipe. The results of this paper provide reference for the fine design of mechanical composite pipe for gathering system.