The genes with significantly different expressions were selected from the different frequency sound gene transcriptomes of Onchidium reevesii. We compared these genes with the genes related to human auditory perception and deafness in IMPC, and the hearing-related gene NXN was discovered. The cDNA sequence of OrNXN gene was cloned by rapid amplification of cDNA ends (RACE) technology, and the sequence was analyzed by bioinformatics; real-time quantitative PCR (qPCR) technology was used to analyze the relative expression in different tissues, different frequency sounds, and different tide nodes. The results show that the length of OrNXN is 1 593 bp with 432 bp of open reading frame. OrNXN protein is encoded by 143 amino acids. The molecular mass of OrNXN is 15.57 ku. Domain prediction analysis shows that OrNXN contains a typical sulfur redox protein structure of the Thioredoxin family. The results of multiple sequence alignment and the phylogenetic tree construction showed that OrNXN has high similarity with other species. The qPCR results show that OrNXN is expressed in the intestine, ganglia, gonads and gastropods of O. reevesii. The expression is highest in the intestine, followed by ganglia. OrNXN is expressed differently at 200 and 50 Hz under different sound frequency stimulation. The relative expression level of OrNXN is different at different tidal nodes, and it basically changes with the tide water level. Studies have shown that OrNXN may respond to the low-frequency sound emitted by the tide when O. reevesii senses the tidal node rate.