A high sensitivity segmented structure optic fiber sensor is proposed, which is based on evanescent wave absorbed theory.The modes of the segmented structure and straight waveguide are simulated and analyzed by using beam propagation method (BPM),which shows that the high-order modes are excited and absorbed repeatedly at the first transition of each segmented region in the segmented structure.The effects o f the different structures,the core diameters and the concentration of solution on the sensitivity of the sensors are investigated,and the sensitivities are tested by using different concentrations of the methylene blue solution.The experiment al results show that with the fixed core diameters,the sensitivity of segmented structure sensors is 0.0380L/g,which is higher than that of the conventional single straight sensor (0.0262L/g),while the sensing region length of the former (1cm) are shorter than that of the latter (5cm).The segmented structure evanescent wave sensor can eff ectively stimulate the fiber low-order modes to the high-order modes,the sensitivity will be higher.The result is co nsistent with theoretical models and simulation analysis.The proposed sensor not only has a high sensitivity,but also is robust due to the larger core diameters and shorter length of the segmented region,which is suitable for mate rials spectrum measurements.