Objective To investigate the effect and possible mechanism of the alcohol extract of Alisma orientalis on thyroid function of mother rats and neurological function of offspring with subclinical hypothyroidism (SCH). Methods A total of 85 female rats were selected, of which 15 rats acted as sham operation group and treated with sham operation, the other 70 rats underwent thyroidectomy + subcutaneous injection of levothyroxine (L-T₄) to establish the SCH model. Sixty-two of the 70 rats were successfully modeled, and randomly divided into low-dose Alisma ethanol extract group (15 rats, gavage with alcohol extract of Alisma orientalis 9 g/kg), high-dose Alisma ethanol extract group (16 rats, gavage with alcohol extract of Alisma 36 g/kg), L-T₄ group (16 rats, gavage with 4.5 μg/kg L-T₄), model group (15 rats, gavage with equal volume of normal saline), once a day, the intervention time is from 10th day of pregnancy (E10) to 21st day after birth (P21). The thyroid stimulating hormone (TSH) and thyroxine (T₄) of female rats at E17 were detected by electrochemiluminescence. ELISA was used to detect the nerve growth factor(NGF) and brain-derived neurotrophic factor (BDNF) in the hippocampus of offspring rats at P21; Western blotting was performed to detect the expression levels of tropomyosin receptor kinase A (TrkA), p-TrkA, c-AMP-response element binding protein (CREB)and p-CREB in the hippocampus of offspring rats at P21; The escape latency of pups at P40 was measured by the positioning cruise experiment, and the number of times the pups crossed the platform at P41 was measured by the space exploration experiment. Results At E17 gestational age, there was no significant difference in serum T₄ among the 5 groups of female mice (P>0.05). The serum TSH levels were lower in low- and high-dose Alisma ethanol extract group and L-T₄ group than that in model group, and the serum TSH levels were lower in high-dose Alisma ethanol extract group and L-T₄ group than that in low-dose Alisma ethanol extract group (P<0.05), while no significant difference existed in serum TSH levels between high-dose Alisma ethanol extract group and L-T₄ group (P>0.05). At P21, the NGF, BDNF, p-TrkA and p-CREB of hippocampus were significantly higher in low- and high-dose Alisma ethanol extract group and L-T₄ group than those in model group. The NGF, BDNF, p-TrkA and p-CREB were obviously higher in high-dose Alisma ethanol extract group and the hippocampus of L-T₄ group than those in the low-dose Alisma ethanol extract group (P<0.05). There was no statistically significant difference on NGF and BDNF between the high-dose Alisma ethanol extract group and the hippocampus of L-T₄ group (P>0.05). The escape latency of offspring rats was shorter in low- and high-dose Alisma ethanol extract group and L-T₄ group than that in model group, and the times of offspring crossing the platform were more than that in model group (P<0.05). The escape latency of offspring in the L-T₄ group was shorter than that in low-dose Alisma ethanol extract group, and the times of offspring crossing the platform was more than that in low-dose Alisma ethanol extract group(P<0.05). There was no significant difference in the escape latency and the times of crossing the platform between high-dose Alisma ethanol extract group and L-T₄ group (P>0.05). Conclusions The ethanol extract of Alisma orientalis applied to SCH mother rats can improve the thyroid function of the mother rats, promote the expression of neurological factors of offspring rats, and improve their learning and memory function. The mechanism may be related to the activation of the expression of TrkA signaling pathway.