Objective To explore the possible mechanism of laryngeal carcinoma treated by combined formula of Erchen Decoction（二陈汤） and Huiyan Zhuyu Decoction（会厌逐瘀汤）. Methods Heterotopic transplantation of Hep2 laryngeal carcinoma cell lines was used to establish the mice model of laryngeal carcinoma. The model mice were divided into a control group

a combined formula low dose

medium dose and high dose group

and a cisplatin group

with seven mice in each group. The combined formula low dose

medium dose and high dose groups were respectively treated with 14.44 g/（kg·d）

28.87 g/（kg·d）

and 57.74 g/（kg·d） of Erchen Decoction and Huiyan Zhuyu Decoction by gavage

once daily. The cisplatin group was given intraperitoneal injection of 2 mg/kg cisplatin

once every other day. The control group was administered with equal volume of distilled water by gavage. All the groups were treated for three weeks. Reverse transcription-polymerase chain reaction（RT-PCR） method was used to detect the mRNA expression of programmed death protein ligand 1（PD-L1） and interleukin 6（IL-6）. Western blotting was performed to detect the protein expression of the mouse tumor tissues PD-L1

protein Janus kinase（p-JAK）

signal transducer and activator of transcription 3（STAT3）

and phosphorylated STAT3（p-STAT3）. The Immunohistochemical detection of PD-L1 protein expression was explored in mouse tumor tissues. Results Compared to control group

the PD-L1 mRNA and protein expression of combined formula low dose

medium dose

high dose groups and cisplatin group significantly decreased; the IL-6 mRNA expression of combined formula low dose

medium dose

and high dose groups significantly decreased; the STAT3 and p-STAT3 protein expression of combined formula medium dose

high dose groups and cisplatin group significantly decreased; and the p-JAK1 protein expression of combined formula high dose group significantly decreased（P<0.01）. The PD-L1 and IL-6 mRNA expression of combined formula high dose group were significantly lower when compared to those of combined formula low dose

medium dose groups and cisplatin group

as well as the PD-L1 protein expression of combined formula high dose group when compared to medium dose group and cisplatin group; the STAT3 protein expression of high dose group when compared to low dose and medium dose groups and cisplatin group; and the p-STAT3 protein expression of high dose group when compared to combined formula low dose and medium dose groups（P<0.05 or P<0.01）. Conclusion When treating laryngeal carcinoma

Erchen Decoction combined with Huiyan Zhuyu Decoction may work through inhi-biting the IL-6/JAK1/STAT3 signaling pathway

and hence reducing the expression of PD-L1 in tumor issues.