Aim To explore the concentration changes of plasma homocysteine (Hcy) and gene mutation of methylenetetrahydrofolate reductase (MTHFR C677T) different type of coronary heart disease (CHD) and different vessel number of coronary artery where found significant lesion by coronary angiography (CAG), analyse the relationship between gene mutation of MTHFR C677T and the levels of plasma Hcy and the relationship between the gene mutation and CHD. Method The total subjects were divided four groups as follows: 74 patients without coronary heart disease (control group), 32 patients with stable angina pectoris (SA), 104 patients with unstable angina pectoris (UA), 25patients with acute myocardial infarction (AMI),which were all documented by CAG. The plasma Hcy was determined by high-performance liquid choromatography (HPLC) assay and the genotypes of MTHFR C677T were determined by PCR-based assay. Results The mean levels of plasma Hcy in CHD were significantly higher than control group, those in the AMI group and UA group were significantly higher than control group and SA group, those in the patients with single-vessel disease was higher than in non-vessel disease or in 1double-vessel, in triple-vessel disease. The mean levels of plasma Hcy in the patients with mutant homozygote for MTHFR C677T was higher than wild homozygote or heterozygote. The incidence rate of gene mutation of MTHFR C677T in CHD were higher than control group, but there was no statistic significance. Correlation analyses showed the correlation coefficient of MTHFR C677T gene mutation to CHD or plasma Hcy was 0.000, 0.000 respectively. Using binary Logistic regression analysis we found the adjusted odds ratio of moderate hyperhomocysteinemia for CHD was 1.138. Conclusion The high plasma Hcy may be independent risk factors of CHD, furthermore, may be the marker of acute coronary syndrome (ACS), but not have positive correlation with the vessel number of coronary artery where found significant lesion by CAG. Methylenetetrahydrofolate reductase C677T gene mutation is neither an independent risk factor of CHD, nor the most important factor determining the concentration of plasma Hcy.