Micro-bend long period fiber gratings (MBLPFG) are presented by pressing a single mode fiber from double sides with two identical grooved plates whose pitch is 600 μm and teeth width is 200 μm. Because the teeth width is smaller than half pitch of the grooved plate,deeper micro-bend modulation in fiber can be made,and so a bigger “AC” cross-coupling coefficient can be achieved. By measuring the transmission spectra of two micro-bend long period fiber gratings with lengths of 6 cm and 12 cm,respectively,the relations between peak loss,out of band loss,full width at half maximum (FWHM) of loss ratio spectra with applied pressure for different grating length are investigated. For the micro-bend long period fiber grating of 12 cm length,near the first saturation pressure,the peak loss reaches 19.2 dB,the FWHM is 20 nm,out of band loss is only 0.26 dB. After over coupling out and back three times,a peak loss of 34 dB is achieved. Then,through analysis from theory and experimental data,it is found that the “AC” cross-coupling coefficient grows linearly with applied pressure,when the pressure on the fiber is less than saturation pressure.