Objective To investigate the relationship between serum lipoprotein associated phospholipase A2(Lp-PLA2) levels and severity of coronary artery disease in patients with stable coronary artery disease (SCAD). Methods 480 cases of patients with coronary heart disease (CHD) diagnosed by coronary angiography (CAG) were enrolled in the study. Among them, there were 218 patients with SCAD (SCAD group) and 262 patients with acute coronary syndrome (ACS) (ACS group).186 cases of patients without history of heart disease or suspected heart disease and without CHD diagnosed by CAG were selected as the non-CHD group. The serum Lp-PLA2 levels were determined by turbidimetric inhibition immuno assay. Results Lp-PLA2 levels and Gensini score in ACS group were higher than those in SCAD group and non-CHD group, and those in SCAD group were higher than non-CHD group. Lp-PLA2 levels in patients with three-vessel coronary artery disease in SCAD group were higher than those in patients with single or double-vessel coronary artery disease, and the levels were higher in patients with double-vessel coronary artery disease than patients with single-vessel coronary artery disease. Lp-PLA2 levels in patients with Gensini score ≥40 points were higher than those in patients with Gensini score < 20 points and Gensini score of 20~39 points, and the levels were higher in patients with Gensini score of 20~39 points than patients with Gensini score < 20 points. Lp-PLA2 levels in patients with unstable plaques in SCAD group were higher than those in patients without plaques and patients with stable plaques, and the levels were higher in patients with stable plaques than those without plaques. Pearson correlation analysis showed that Lp-PLA2 level was positively correlated with the number of lesions and Gensini score. Conclusion The serum Lp-PLA2 level in patients with SCAD is higher than that in patients without CHD. The level is positively correlated with the severity of coronary artery disease, and can reflect the instability of plaque.