Carbon dioxide and cosolvents have synergistic effect on enhancing oil recovery. Measuring the cloud-point pressure and miscibility pressure is of great significance to improve oil recovery and CO₂ sequestration. Based on the photosensitive principle， the cloud-point pressure of diethylene glycol dimethyl ether（DDME），triethylene glycol dimethyl ether（TEDM）and tetraethylene glycol dimethyl ether（TGDE）in CO₂ and the effects of temperature，concentration and type of the cosolvents were obtained using the improved carbon dioxide phase equilibrium experimental device. Then the effects of cosolvents on decreasing the miscibility pressure of CO₂ -C₁₆ were investigated and compared with that of ethanol. The results showed that the cloud-point pressure of DDME，TEDM and TGDE all increased with the increase of temperature，and then the phase behavior of low critical solution temperature（LCST）was present. With the increase of cosolvent dosage，the cloud-point pressure of DDME，TEDM and TGDE all increased with a low increasing rate. Because the polarity became larger and larger in the order of DDME，TEDM and TGDE，the interaction force between cosolvent and CO₂ became weaker and weaker，leading to the increase of cloud-point pressure. Among the three ether cosolvents with similar structure，DDME had the lowest cloud-point pressure，while TGDE had the highest cloud-point pressure. When the mass fraction of DDME was 3.0%，the cloud-point pressure was only10.14 MPa at 60 ℃. Moreover，DDME had the best effect to decrease the miscibility pressure between CO₂ and C₁₆ . DDME with the dosage of 1% could decrease the miscibility pressure with the decreasing degree of 11.25%，which was larger than that of ethanol（10.62%）at 50 ℃. When the temperature was lower than 50 ℃，the effect of TEDM was better than that of ethanol. At a higher temperature，the effect of ethanol was slightly better than that of TEDM and TGDE. DDME，with a low cloud-point pressure value，a high ability to decrease the miscibility pressure，and a good compatibility with carbon dioxide，was also suitable for the application in the reservoir with low formation pressure.