A high precision transverse pressure sensing system using mechanically-induced long period fiber gratings(MLPFG), is designed and studied experimentally. 60 mm-long periodic pressure grooves are made by mechanical line processing technology with the groove period of 600 μm. The relation between transverse pressure and MLPFG resonance peak is measured. Furthermore, a demodulation system is constructed employing a fiber Bragg grating(FBG), the results show that MLPFG transverse pressure has good linear relation with MLPFG resonance peak in the range of 0～60 N. Linearity is up to 0.9950 and the sensitivity is about 0.35 dB/N. Keeping the MLPFG transverse pressure 45 N for more than 20 h, the MLPFG resonance peak′s maximum fluctuation is less than 0.06 dB. The FBG with central-wavelength at 1542.890 nm is adopted to realize system demodulation, the system sensitivity is 0.12 μW/N, and the practicality of detecting system is further improved.