ObjectiveTo observe ovarian microvascular damage in rats with cold coagulation and blood stasis syndrome and to explore the mechanism by which Liangfang Wenjing decoction improves this condition in rats. MethodsFifty SPF female SD rats were randomly divided into a blank group， a model group， low-dose （8.1 g·kg^-1） and high-dose groups （16.2 g·kg^-1） of Liangfang Wenjing decoction， and a 4-phenylbutyric acid （0.1 g·kg^-1） group， with 10 rats in each group. The ice-water bath method was employed to establish the rat model of cold coagulation and blood stasis syndrome. Concurrent with modeling， Liangfang Wenjing decoction was administered continuously for 21 days， once daily. The rats' syndrome manifestations and estrous cycles were recorded. The enzyme-linked immunosorbent assay （ELISA） was used to detect serum reproductive hormone levels and levels of endothelin-1 （ET-1）， nitric oxide （NO）， thrombomodulin （TM）， and von Willebrand factor （vWF） in ovarian tissue. Prothrombin time （PT）， activated partial thromboplastin time （APTT）， thrombin time （TT）， and fibrinogen （FIB） were measured. The ovarian microcirculatory blood perfusion was detected by laser speckle contrast imaging. Hematoxylin-eosin （HE） staining was performed to observe the ovarian histopathology， flow cytometry to detect ovarian apoptosis rate， and transmission electron microscopy to observe the ultrastructure of ovarian microvascular endothelial cells. Western blot was employed to detect the protein expression of endothelial nitric oxide synthase （eNOS）， phosphorylated eNOS （p-eNOS）， Caspase-3， B-cell lymphoma-2 （Bcl-2）， Bcl-2-associated X protein （Bax）， glucose-regulated protein 78 （GRP78）， C/EBP homologous protein （CHOP）， inositol-requiring enzyme1α （IRE1α）， p-IRE1α， apoptosis signal-regulating kinase 1 （ASK1）， p-ASK1， c-Jun N-terminal kinase （JNK）， and p-JNK. Immunofluorescence was used to detect ovarian Bax and Bcl-2 expression in microvascular endothelial cells. ResultsCompared with the blank group， the model group showed signs of cold coagulation and blood stasis syndrome， prolonged estrus cycles， and reproductive hormone disorders. Histopathological results revealed a decrease in follicle counts at all stages and disorganized granulosa cell arrangement. Ovarian microcirculatory perfusion was significantly decreased （P<0.01）. PT， APTT， and TT were reduced （P<0.05， P<0.01）， while FIB levels were increased （P<0.05）. In ovarian tissue， NO content was decreased， while ET-1， vWF， and TM levels were increased significantly （P<0.01）. The apoptosis rate of ovarian cells was markedly increased （P<0.01）. Furthermore， p-eNOS/eNOS and Bcl-2 were decreased （P<0.05）， whereas Bax， cleaved-Caspase-3/Caspase-3， GRP78， CHOP， p-IRE1α/IRE1α， p-ASK1/ASK1， and p-JNK/JNK expression showed significant increases （P<0.05， P<0.01）. Compared with the model group， Liangfang Wenjing decoction intervention alleviated the symptoms of cold coagulation and blood stasis， gradually restored the estrus cycle， and improved ovarian histopathology and endothelial cell ultrastructure. Microcirculatory blood perfusion was significantly elevated （P<0.05）. NO content in ovarian tissue was elevated， while ET-1， vWF， and TM levels were significantly decreased （P<0.05， P<0.01）. The p-eNOS/eNOS ratio and Bcl-2 expression were significantly elevated （P<0.05）， while the expression of Bax， cleaved-Caspase-3/Caspase-3， GRP78， CHOP， p-IRE1α/IRE1α， p-ASK1/ASK1， and p-JNK/JNK was significantly decreased （P<0.05， P<0.01）. ConclusionLiangfang Wenjing decoction may regulate the IRE1α/ASK1/JNK signaling pathway to inhibit endoplasmic reticulum stress， attenuate apoptosis， and improve microvascular endothelial injury in ovaries of rats with cold coagulation and blood stasis syndrome.