Objective. To evaluate the application value of serum lipoprotein-associated phospholipase A2 (Lp-PLA2) and homocysteine (Hcy) combined with color Doppler detection in elderly patients with acute coronary syndrome (ACS) and the influence on their endothelial function. Methods. From February 2019 to October 2020, 100 elderly patients with suspected ACS treated in our hospital were recruited and assigned (1 : 1) to a control group or an experimental group. The control group received color Doppler detection, and the experimental group received the combined detection of serum Lp-PLA2 and Hcy and color Doppler. Positive results were determined by the combined detection of the levels of LP-PLA2 and Hcy and color Doppler. The two groups were compared in terms of specificity, susceptibility, positive detection rate, negative detection rate, test accuracy, the area under the receiver operating characteristic (ROC) curve (AUC), the expression levels of interleukin-2 (IL-2), interleukin-12 (IL-12), interleukin-13 (IL-13), and the vascular endothelial function. The patients with ACS were divided into three subgroups according to the Gensini score three-quartile interval, and their Lp-PLA2 levels were calculated for analysis. Results. The test specificity, susceptibility, positive detection rate, negative detection rate, test accuracy, and AUC in the experimental group were much better than the those in the control group (all
P
<
0.05
), and there were no significant differences in the expression levels of IL-2, IL-12, IL-13, and vascular endothelial function between the two groups (
P
>
0.05
). The three subgroups showed similar levels of fasting blood glucose, total cholesterol, triglyceride, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, apolipoprotein A-I, glutamic-pyruvic transaminase, lutamic-oxaloacetic transaminase, homocysteine, and amino-terminal pro-brain natriuretic peptide (all
P
>
0.05
). The severe condition group had the highest Lp-PLA2 level, followed by the moderate group, and then the mild group (
P
<
0.05
). Moreover, the levels of LP-PLA2, aspartate transaminase (AST), and N-terminal pro hormone B-type natriuretic peptide (NT-proBNP) were all influencing factors for the coronary Gensini score (all
P
<
0.05
). Conclusion. The combined detection of serum Lp-PLA2, Hcy, and color Doppler significantly improves the diagnostic accuracy, specificity, and susceptibility in the elderly with ACS, with little impact on their vascular endothelial function.