Blood clam (Tegillarca granosa), as a common farmed bivalve in tidal flat shellfish, has high economic value. Conditional pathogenic bacteria, such as Vibrio, is a serious problem encountered in the healthy culture of bivalve shellfish. To explore the role and mechanism of JNK-mediated AP-1 innate immune defense pathway in the process of vibrio infection, the cDNA sequence of TgJNK was cloned by PCR, and the expression and regulatory relationship of TgJNK and TgAP-1 after vibrio infection were analyzed. The results showed that the fulllength of the TgJNK cDNA sequence was 2696 bp with an open reading frame of 1,332 bp, encoding a 443 amino acid polypeptide. Multiple protein comparison and adjacent phylogenetic tree analysis showed that TgJNK was relatively conservative with a STKc-JNK domain and had high homologous similarity with Crassostrea gigas and Mytilus edulis. The qRT-PCR and WB analysis showed that TgJNK was highly expressed in the gill. The level of TgJNK transcription was up-regulated significantly (P＜0.05) with immersion infection of Vibrio harveyi. At the same time, the phosphorylation level of TgJNK and the abundance of TgAP-1 protein increased under the stimulation of vibrio. The effect of the JNK inhibitor could significantly decrease the transcription level of TgJNK and TgAP-1(P＜0.05). Correspondingly, the phosphorylation of TgJNK and the abundance of TgAP-1 protein decreased after JNK inhibition. In addition, CoIP analysis showed that the phosphorylated JNK protein could bind to TgAP-1 protein. These results indicated that TgJNK and TgAP-1 participated in the innate immune response of Vibrio infection in blood clams. The phosphorylation of TgJNK protein was an important factor in activating TgAP-1 protein, and TgJNK could positively regulate the expression of TgAP-1. The study elucidated the signal transduction mechanism of JNK-mediated AP-1 pathway after vibrio infection and enriched the theoretical knowledge on the innate immunity of bivalve shellfish.