Aiming at problems of facing in application of transmission mode of photonic crystal fiber（ PCF）sensing technique and nonlinear sensing system mutation

detection precision reducing with mode change

develop a low loss and high anti pressure gas detection photon crystal optical fiber sensor. According to nonlinear sensing system and band gap material layout of photonic crystal fiber

establish loss analysis model and summarize effect of distance of holes and diameter of cladding on loss

and establish loss awaring algorithm. Compare effects on singlemode

second order model and heterogeneous hole on loss

establish mode adaptive modulation algorithm; develop a loss perceived support adaptive modulation mode photonic crystal fiber sensor for gas detection. Experimental results of measurement system prove that advantages of the reliability and the superiority of the fiber sensor developed by the proposed scheme in aspects of loss

detection precision and compression.