To study the toxic effect of nonylphenol on Rana nigromaculata blood,osmotic pressure and blood cells were researched.200,400 and 600 mg/kg nonylphenol were injected in R.nigromaculata by the abdominal lymph capsule separately,and a vapor pressure osmometer was used to measure blood osmotic pressure in different time.At the same time,blood smears were done to observe the abnormalities of blood cells.The results showed that at the same treated time,plasma osmolality increased in R.nigromaculata with the increasing concentration of nonylphenol.The blood cells enlarged,blood cell nucleolus splited,the phenomenon of uneven quality were observed obviously.At the same treated group,with the increasing concentration of nonylphenol,blood osmotic pressure increased,blood cells enlarged,the nucleus damage was aggravated.Nonylphenol could induce the micronucleus(MN) and other nuclear anomalies(ONA) in erythrocytes of peripheral blood.With nonylphenol concentration increasing,the rate of MN and ONA increased first and decreased last.The rate of MN and ONA decreased with the treated time expand.