Plants in Acaceae family are often considered as ornamental and medicines. However many of them have irritation properties. As medicinal plants some of them are recorded in Chinese Pharmacopoeia and they are figured as poisonous. Through investigating the domestic and overseas studied paper, the needle-like calcium oxalate crystal exits in the plants of Acaceae family could be thought as irritation components of them. This conclusion is same with the studied conclusion of our study group in the medicines plant of Pinellia ternate belonging to the Acaceae family and our studies showed that the needle-like calcium oxalate crystal was the main irritation component of raw P. ternate. The irritated mechanism of raphides is relevant to its special shape, the protein enzyme adhering to it and idioblasts in plants.