Objective To investigate the mechanism by which Yangmai Tongluo formula improves microcirculation disorders induced by high homocysteine (Hcy) levels via regulation of the acid sphingomyelinase (ASM) and endoplasmic reticulum (ER) stress pathways. Methods Fifty male C57BL/6J mice were divided randomly into a control group, Hcy model group, Yangmai Tongluo formula low-/high dose groups (5.3, 10.4 g/kg, respectively), and a folic acid group (0.08 g/kg). Except for the control group, microcirculation disorders were induced in all mice using drinking water containing 1.8 g/L Hcy for 6 weeks. After modeling for 2 weeks, mice were administered the corresponding treatments by gavage for 4 weeks. Serum Hcy concentrations and the blood perfusion volume of the lower extremity microvessels were measured. Protein expression levels of zonula occludens ZO-1, ZO-2, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), ASM, glucose regulated protein 78 (GRP78), and C/EBP homologous protein (CHOP) in the cardiac microvascular endothelium were analyzed using immunofluorescence. Results Serum Hcy levels were significantly increased in the Hcy model group compared with the control group (P<.05). Yangmai Tongluo formula did not significantly reduce Hcy levels compared with the Hcy model group, but blood perfusion in the lower extremities was significantly increased (P<.01) and expression levels of ZO-1 and ZO-2 in the cardiac microvascular endothelium were restored (P<.001) in the Yangmai Tongluo formula high dose group. It also inhibited the expression of ICAM-1, VCAM-1, ASM, GRP78, and CHOP (P<.05), with comparable effects to folic acid. Conclusions Yangmai Tongluo formula improves Hcy-induced microcirculation disorders and endothelial dysfunction by inhibiting ASM activity and alleviating ER stress, via a mechanism closely related to the regulation of endothelial inflammation and barrier stability. These result provide experimental evidence to support the use of traditional Chinese medicine to treat microvascular diseases.