In order to study the basic characteristics of Arundo donax chars obtained by lowtemperature pyrolysis. The Arundo donax char was prepared by using a mediumtemperature tube furnace at the pyrolysis temperatures of 350, 450, 550 and 650 ℃. The weight loss rate, chemical composition, microscopic morphology, combustion reactivity and gasification reactivity of the biochar were studied. The study found that the volatilization of the biochar was greatly reduced, but the fixed carbon content was greatly increased. The biochar achieved a more developed pore structure and the combustion and gasification reactivity changed with the pyrolysis temperature and time. The pyrolysis violent reaction zone was in the range of 350450 ℃, during which a large amount of volatile matter escaped. When the pyrolysis temperature was greater than 450 ℃, the weight loss rate, microscopic morphology, combustion reactivity and reactivity changed little.