A novel automatic profilometry technique by dual-frequency of optical fiber projection grating is introduced. A one to two (1×2) optical fiber coupler is utilized to generate sinusoidal intensity projection grating. A piezoelectric (PZT) cylinder wrapped by one arm of the optical fiber coupler is utilized to introduce phase shift. Different frequencies of projection gratings can be got easily through adjusting the separate distance of the two projecting optical fiber ends. Three-dimension shape can be measured automatically with this technique even in the cases of true discontinuities and noise in the phase.