The writing of an internal diffraction grating in optical glass plate is demonstrated using low-density plasma formation excited by a high-intensity femtosecond Ti:sapphire laser. The same diffraction efficiency at +-1, +-2, and 0 order isachieved by multiple layers writing. The dependences of diffractive efficiency on the irradiated energy, the speed of writing, the numerical aperture (NA) of the focusing objective, and materials are investigated in detail. The grating isbirefringent. It is attributed to residual stress interaction between glass and femtosecond laser pulse.