A novel three-dimensional shape measurement method is presented for low current tungsten inert gas welding pool surface, based on fringe reflection and Fourier Transform Profilometry (FTP). The relationship between surface height and phase variation has been demonstrated. Reflection character of liquid metal on welding pool surface and scattering function result from molten pool concussion have been discussed with the purpose of taking the picture of reflected deformed laser stripes by means of pool height measurement device. The obtained deformed laser stripes of low current tungsten inert gas weld pool surface were processed by computer to acquire pool surface height. An experiment has been done to demonstrate that Fourier transform profilometry is suitable for three-dimensional shape measurement of three-dimensional shape measurement.