The surface temperature and equivalent heat conductivity of Flat Plate Heat Pipe (FPHP) under different heat flux, liquid filling and tilt angles are investigated experimentally. Electrical discharge machining (EDM) micro-channels wick are select as the wick inside FPHP. A set of experimental facility to measure the temperatures of FPHP is build up. The surface temperature along channels under different tilt angles, liquid filling and heat flux are measured by thermal couples. The results indicate that the temperatures are independent to the tilt angles and liquid filling. The equivalent thermal conductivity increases with the increasing of heat flux, and is 1.36 to 1.44 times to that of brass.