Abstract: A new type of radiochromic gel composite, which was composed of acrylamide gels as carrier and diacetylene (10, 12-pentacosadiynoic acid) vesicles as chromogenic agent, was prepared, and its radiochromic properties were studied. The color of the gel composites changed from colorless to blue after irradiation. The main absorption peak at around 660 nm appears in the UV-Vis spectroscopy, and its absorbance has a linear relationship with the absorbed dose. For comparison purpose, the diacetylene vesicles were irradiated and analyzed by Raman spectroscopy. The results show that the peak at 2200 cm^-1 in Raman shift corresponding to C≡C—C≡C vibration gradually attenuates and disappears, and the peak at near 2 100 cm^-1 corresponding to C≡C—C=C vibrations moves to a lower wavenumber with the increasing absorbed dose. These results indicate that the diacetylene vesicles are polymerized gradually during irradiation. The dose-rate effect, the fractionated-irradiation effect and the diffusion-effect of the diacetylene gel composites were studied additionally. The dose rate shows negligible influence on dose response in the range of 2.40 Gy/min. The dose response with the fractionated irradiation up to a certain dose is consistent with a single continuous irradiation. There is no obvious diffusion effect in diacetylene vesicles embedded in acrylamide gels. Based on the results above, the diacetylene gel composites are promising to be used in measuring the three-dimensional space dose, and the range of dosage measuring is about 100-2000Gy.