Objective: To explore the changes of peripheral leukocyte’s telomere length (LTL) in patients of premature coronary artery disease (PCAD) with inlfuencing factors. Methods: Our research was conducted in 2 sets of groups, by coronary artery condition: PCAD group,n=128 including 88 patients with ACS, 40 with SCAD and Non-CAD group,n=128 subjects; by age status: the age≤30 years, 31-40 years, 41-50 years, 51-60 years had 2, 14, 65, 47 patients in each group respectively. Peripheral LTL was detected by lfuorescent quantitative analysis, the relationship between LTL and PCAD with inlfuencing factors were studied by Spearman correlation analysis. Results: In PCAD group, compared with SCAD patients, ACS patients had more male gender, higher Gensini score, lower T/S ratio and shorter LTL, allP<0.05. Compared with Non-CAD group, PCAD group had decreased T/S ratio (0.88 ± 0.86) vs (1.10 ± 0.57),P<0.05. T/S ratio was negatively related to age in both PCAD group (r=-0.275,P=0.002) and Non-CAD group (r=-0.316,P=0.000). Spearman correlation study presented that in PCAD group, LTL was negatively related to hyperlipidemia (r=-0.415,P=0.049) and diabetes (r=-0.472,P=0.036); multi linear regression analysis indicated that in PCAD group, LTL was negatively related to age (B=-0.023,P=0.038) and in Non-CAD group, LTL was negatively related to age (B=-0.027,P=0.000), smoking (B=-0.278,P=0.012), HDL-C (B=-0.297,P=0.046). Conclusion: PCAD had more male ACS patients with shorter LTL and severer coronary lesions; LTL was negatively related to hyperlipidemia and diabetes, age was an important inlfuencing factor for LTL shortening.