Intelligent well hydraulic control pipeline temperature changes in a complex environment,and the hydraulic oil contains a small amount of gas,directly affecting fluid properties in the line,which affects the pressure in the pipeline,the accuracy of the flow pressure signal and pressure fluctuations caused by potential water hammer problem,even leads to downhole hydraulic control tool cant normal operation.The conventional one-dimensional transient flow analysis of pipeline system is established without considering heat exchange or temperature change,which results in a large error between the calculated end pressure value and the end water hammer pressure.Therefore,on the basis of the traditional transient flow equation calculation,considering the influence of temperature change and gas content on hydraulic oil density,viscosity and volume modulus,the transient flow calculation model of downhole control pipeline with significant temperature change was optimized.Taking No32 hydraulic oil as an example,one-dimensional calculation of the non-constant temperature transient flow model of underground pipeline was carried out by using the characteristic line method,and the end pressure flow signal and pressure fluctuation when water hammer was generated with different temperature and gas content under the influence of geothermal gradient were comparatively analyzed.It provides an idea for solving transient flow in non-constant temperature pipeline,and the numerical results can provide a reference for accurate control of opening action of intelligent well flow control valve and water hammer protection of decoder system.