Sustained toxicity of butylbenzyl phthalate in vivo of rat was evaluated at a dose of 1000, 500 and 250 mg/kg for 6 weeks and 20 weeks. The results show that butylbenzyl phthalate induce a decrease incidence of rats' testicle (p less 0.01), epididymides and prostate (p less 0.05). And tumefaction of liver (p less 0.01) is found. Histopathologic change is observed on testicle, prostate (p less 0.05) and liver (p less 0.01). Especially butylbenzyl phthalate can induce atrophy and denaturalization of convoluted seminiferous tubule and decreasing of spermatogenic cell on all levels. Configuration of spermatogenic cell and Sertoli cell is markedly in disorder. Conjunctive configuration between cells disappeared. In serum the activity of gamma-G (p less 0.01) and ALP (p less 0.05) and the level of testosterone (p less 0.01) are reduced. In opposition the activity of LDH (p less 0.01) and the level of FSH (p less 0.01) are increased. The alterations present hypotaxis of dose-effect and time-effect. Combining with the alteration of histopathology and sex hormone, it shows butylbenzyl phthalate's target cell is Sertoli cell and the chondriosome is its target. Butylbenzyl phthalate induces female rats accretion of uterus, slight inflammation of histopathology and decreasing of ALP's activity (p less 0.05). All the evidences adequately prove that sexual difference exists for animals' disturbance. Butylbenzyl phthalate is more harmful for male than female.