A loop heat pipe structure includes an evaporator and a first pipe. The evaporator has a first chamber, a first wick layer, and a bottom. The first wick layer is provided in the first chamber. The first pipe includes a first inlet and a first outlet communicably connected to the evaporator. The first inlet internally defines a second chamber communicable with the first wick layer. By providing the second chamber outside the evaporator, the evaporator can have a reduced overall height without creating very high vapor pressure in the evaporator, enabling the loop heat pipe structure to have upgraded heat dissipation efficiency.