Aim To explore the relationship between the low density lipoprotein particle size, percent of small density low-density lipoprotein （sd-LDL） and the coronary artery disease with its severity. Methods Our work includes 2 groups, coronary artery disease （CAD） group （n＝60）, consecutive patients with coronary angiography （CAG） confirmed by diagnosis, and control group （n＝30）,healthy control. The LDL sub-fraction was quantified by Lipoprint system and the low density lipoprotein particle size, percent of small density low-density lipoprotein and the coronary artery disease with its severity were studied. Results Compared with control group, CAD group had smaller low density lipoprotein particle （265.0±4.2 vs 267.9±3.9, P<0.05）, increased percent of type B and small density low-density lipoprotein （43.3% vs 20.0%, （15.36%±10.74% vs 9.57%±7.55%, P<0.05）. Multivariate Logisitic regression analysis presented that BMI and sd-LDL were the independent predictions for CAD. Single faction analysis variance indicated that compared with single diseased coronary branch, the patients with multivessel disease had smaller low density lipoprotein particle （264.1±3.3 vs 265.7±3.5, P<0.05）, higher percent of small density low-density lipoprotein （16.80%±10.87% vs 11.50%±8.38%, P<0.05）. The low density lipoprotein particle size was negatively related to Gensini scores （r＝－0.430, P<0.01） and TG （r＝－0.408, P<0.01）. Conclusion Sd-LDL is obviously related to CAD occurrence, and decreased low density lipoprotein particle size and increased percent of small density low-density lipoprotein are associated with CAD severity.