In the sixth generation mobile communication network (6G), in order to solve the problem of smooth handover of quantum mobile terminals in overlapping regions of different cells, this paper proposes a soft handover strategy based on optimal entanglement degree. By establishing a calculation model of the optimal entanglement degree between the mobile terminal Alice and the current cell A, and the target cell B, the change trend of entanglement between Alice and different cells is in the process of motion is analyzed, and the cell corresponding to optimal entanglement degree is obtained. Through simulation, the characteristics of hard handover and soft handover are compared. The results show that as the distance between Alice and A-cell increases, the degree of entanglement between them decreases gradually. As Alice gradually approaches B-cell, the entanglement degree between Alice and cell B increases. If the B-cell is the optimal entangled cell, there will be a short link interruption during hard handover, and soft handover can achieve smooth handover between cells. It can be seen that in the 6G networking, the optimal entanglement soft handover strategy can effectively improve the communication connection rate during the handover process.