A novel low cost sensing system for simultaneous measurements of temperature,strain and torsion based on unique optical characteristics of long period fiber gratings(LPFGs) and ultra-long period fiber gratings(ULPFGs) induced by high frequency CO₂ laser pulses was reported in this paper. Here an intensity-type demodulating approach which can satisfy the real measurement was realized based on the edge filtering effect of the LPFG and the ULPFG. The experimental results show that the sensitivities of temperature and strain are －0.211 dB/℃ and －0.012 dB/10με,respectively. And the sensitivity of torsion is 0.4394 dB/(rad·m^－1),which is 4 times over than that of normal LPFG.