Abstract: To satisfy the increased requirements in quantitative defect depth measurements, pulse phase thermograph is proposed based on the property of pulsed infrared thermal wave nondestructive testing.Pulse phase thermograph transforms the flat bottom samples temporal signals to phase thermographs by Fourier transformation in VC++,gets the blind frequencies and calculates the depths.Initial results gave different calibrated curves and error analyses.It showed that the method provides an assistant way for subsurface defects detection of materials and structures.