Loop Heat Pipe (LHP) is an efficient two-phase heat transfer device, which can be used in waste heat recovery, electronics cooling, aerospace and other fields. The wick, the core component of LHP, plays an important role in its start-up and operation. In this paper, the wick fabricated by 3D printing technology had uniform and interconnected pores. In the experiment, the position of the parallel vapor removal grooves was always fixed towards the vapor outlet. When the cylindrical wick was placed in the evaporator, the rotation angle relative to its central axis could be changed, thus changing the number and shape of the pores facing the vapor removal grooves. The wick deflection angle represented its change in spatial position relative to the fixed vapor removal grooves. The effect of the wick deflection angles on the heat transfer characteristics of the flat LHP was experimentally investigated. It was found that with the change of deflection angle, the number of pores in the evaporation-oriented zone would also change, which had a significant impact on the start-up process and heat transfer performance of LHP. When the deflection angle was 30°, LHP could start fastest at a low heat load of 20 W and operate stable at a high heat load of 180 W.