This study established a Chinese scale for measuring high school students' ocean literacy. This included testing its reliability, validity, and differential item functioning (DIF) with the aim of compensating for the lack of DIF tests focusing on current scales. The construct validity and reliability were verified and tested by analyzing the established scale's items using the Rasch model, and a gender DIF test was conducted to ensure the test results' fairness when distinct groups were compared simultaneously. The results indicated that the scale established in this study is unidimensional and possesses favorable internal consistency and construct validity. The gender DIF test results indicated that several items were difficult for either female or male students to correctly answer; however, the experts and scholars discussed these items individually and suggested retaining them. The final Chinese version of the ocean literacy scale developed here comprises 48 items that can reflect high school students' understanding of ocean literacy--which helps students understand the topics of marine science encountered in real life.