Abstract: The difference between the room and the in-situ temperatures leads to that of the measured physical and mechanical parameters of marine sediments. Based on the temperature-controlled triaxial apparatus, the consolidated undrained shear tests are carried out on the undisturbed marine sediments from the South China Sea. The changes of deformation, strength, pore pressure and modulus of the marine sediments are measured, and the influences of temperature, temperature cycle, confining pressure and over-consolidation ratio (OCR) on the mechanical properties of the undisturbed marine sediments are discussed. The results show that the increase of the temperature gradient increases the degree of thermal consolidation of the normally consolidated marine sediments, and the corresponding drainage volume and strength also increase. The temperature increases the drainage volume of the over-consolidated marine sediments, while the temperature decreases the strength of the marine sediments. The temperature cycle can enhance the drainage volume of the over-consolidated marine sediments, and its corresponding strength also increases. When OCR=1, the measured undrained shear strength of marine sediments at 25℃ is 8.0% higher than that at 5℃. When OCR=4, the measured undrained shear strength of marine sediments at 25℃ is 1.9% lower than that at 5℃. The shear strength after the temperature cycle of 5℃—45℃—5℃ is 11.9% higher than that at 5℃. After 4 or 10 temperature cycles, the shear strength increases by 13.8% and 17.8%, respectively.