Objective to investigate the health changes of patients with severe trimethyltin chloride (TMT) poisoning in four years. Six patients with severe TMT poisoning treated in the First Affiliated Hospital of Gannan Medical College in August 2016 were numbered 1, 2, 3, 4, 5 and 6 respectively. The patients were followed up 0.5, 2 and 4 years after poisoning and compared and analyzed. The follow-up contents include: symptom degree, score of simple mental intelligence examination scale (MMSE) and modified Rankin Scale (MRS) , cranial magnetic resonance imaging (MRI) , EEG, etc. The symptoms of dizziness, headache, chest tightness, palpitation, nausea and vomiting decreased gradually in 6 patients. The symptoms of speech disorder and memory decline in No.1, 2 and 3 patients gradually increased, and the scores of MMSE and Mrs gradually decreased; Patients No.4, 5 and 6 had improved speech disorder, but their memory decreased, MMSE and Mrs scores were still flat, and mild cognitive impairment. The brain atrophy of No.1, 2 and 3 patients was aggravated, which showed obvious atrophy of hippocampus, temporal lobe, insular lobe and cerebellum and enlargement of ventricle; There was no significant change in brain atrophy in No.4, 5 and 6 patients. The neurotoxic symptoms in the later stage of severe TMT poisoning are still serious, and the neurotoxic time is long.