Provide the basis for clinical pathogeny diagnosis and discuss effective ways of curing the youth cerebral infarction in different TOAST classifications through analysis of the correlation between the youth infarction in different TOAST classifications and high homocysteine (Hcy). The selected young patients who diagnosed with cerebral infarction and admitted to the hospital in the past 3 years were regarded as the study group, and the other 136 persons picked accepted health examination in our hospital in the corresponding period were regarded as the control group, then the 136 patients were grouped according to TOAST classification; Hcy levels were determined by enzymatic cycling to compare and analyze, and NIHSS scale is applied to score. Compared with the control group, serum Hcy levels in young patients with cerebral infarction were significantly higher (P < 0.05). The statistical significance in comparative difference was found in the serum Hcy level and NIHSS score of large artery atherosclerotic (LAA) subtype from TOAST classification and the other four subtypes (P < 0.05), but such significance was absent among the other four subtypes (SAA, CA, SOE, SUE). In conclusion, the cerebral etiology of high Hcy is often related to the atherosclerosis and tends to be more serious than the other subtypes after onset of LAA, which requires more clinical attention. Early intervention and therapy are highly necessary specific to cause of disease.