We propose a new method to design a phase-shifted long period grating(PSLPG) by adding an embedded-modulation structure in a long period grating at some position.The spectral characteristics are obtained by the transfer matrix simulated approach.The studies show that when a uniform short grating embedded-modulation structure,which has the same modulated depth but different period with the original one,is added in a long period grating,the grating also could be seen as a single phase-shifted long period gating,and the magnitude of phase-shifting is the sum of the two modulation structures in the embedded-modulation structure.Furthermore,we fabricated the embedded-modulation PSLPG by CO2 laser exposure,and the experiment agrees well with the theory.