The ampacity of submarine cables is an important parameter for its operation and scheduling, which is restricted by the maximum allowable operating temperature of submarine cables. It is of great significance to establish the temperature field and ampacity model of submarine cables considering the influence of ocean currents in complex submarine environment. In view of the complicated calculation of the traditional analytical method and just suitable for specific laying environment and other problems, according to the electroheatflow multifield coupling theory, based on the finite element analysis technology, the temperature field and ampacity analysis model of highvoltage threecore XLPE submarine cable under the two laying methods of burying and laying are established respectively, and studied the influence of ocean current velocity and temperature on the ampacity. The research results show that the relative error between the proposed model with the traditional analytical method is within 5%; the steadystate ampacity of the laid cable is 200~330 A higher than the buried under the same environmental factors, and the change rate of the two methods is more sensitive at low current rates, but it is not affected by the temperature of the ocean current. In addition, the allowable operating time of shortterm emergency ampacity is inversely proportional to its size and initial cable core temperature.