To study the correlation of Pinellia ternata agglutinin (PTA) and toxicity of P. ternata raphides and to find out the toxic mechanism of P. ternata.PTA has obvious effect of pro-inflammation. The model of rats peritonitis was used to study the dose-toxicity and time-toxicity relationship of the effect by detecting the releases of inflammatory mediators PGE2 in the exudates. The model of Draize rabbit eye test was applied to determine the correlation of PTA and toxicity of raphides by pathological examination.PTA enhanced the content of PGE2 and protein in rats peritoneal cavities concentration dependently. With PTA concentration increased, PTA enhanced the inflammation induced by raphides to rabbit eyes, but PTA alone had no toxicity response.PTA had obvious effect of pro-inflammation. The toxic mechanism of P. ternata was PTA induced inflammation only when the raphides pierce into the organization.