In order to evaluate the effects of lanthanum nitrate on the development of the parent, offspring, and the third generation of Sprague-Dawley (SD) rats, a two-generation reproductive toxicity experiment, was conducted. Two hundred and forty specific pathogen-free (SPF) healthy SD rats were randomly divided into the control group, low-, medium-, and high-dose group, with 30 male and 30 female rats in each group. The rats in each group were given 0 mg/kg, 10.0 mg/kg, 30.0 mg/kg, and 90.0 mg/kg lanthanum nitrate by gavage, respectively. There was no statistically significant difference between the weight gain and food intake of rats in each group. High-dose lanthanum nitrate had no effect on rat implantation and no embryo toxicity. The absolute and relative liver weights of F1a and F1b male rats in the high-dose group were significantly decreased. The absolute liver and spleen weight of F1b female rats in the high-dose group decreased significantly, but the relative weight did not change significantly. Histopathological examination results showed that there were no significant differences in the effects of different doses of lanthanum nitrate on the uterus, ovaries, oviduct, testes and epididymis, and liver of SD rats. Under the experimental conditions, 90.0 mg/kg lanthanum nitrate had an effect on the liver weight of the SD rats, but there was no liver toxicity. The no visible harmful effect level (NOAEL) of lanthanum nitrate on SD rats' reproduction toxicity is 90 mg/kg.