Photocatalytic technologies are expected to solve the problem of organic matter pretreatment in nuclear wastewater to realize the sustainable development for energy and environment. However, the design and synthesis of the low-cost and high-efficiency photocatalysts are a significant challenge to achieve this goal. In this work, the 2D/2D g-C 3 N 4 /1T-MoS 2 Schottky heterojunction photocatalyst was prepared by a liquid-phase ultrasonic self-assembly method, and the enhanced carrier separation ability was proved by the electrochemical impedance spectroscopy, transient photocurrent, and photoluminescence spectra, which improved the photocatalytic quantum efficiency. The results suggested that the 2D/2D g-C 3 N 4 /1T-MoS 2 heterojunction not only has a satisfactory ability to treat tannic acid in nuclear wastewater but also has excellent removal effects on various dyes including methylene blue, rhodamine B, methyl violet, amaranth, and methyl orange. This work provides an effective approach to construct the 2D/2D Schottky heterojunctions for the application in photocatalytic spent fuel wastewater or industrial sewage treatment.