The monitoring of reactive oxygen species (ROS) in biological system has been occupying research hotspots recently, since the biochemical alterations caused by the overproduction of ROS are the main incentives of diseases and accelerated aging process. In this work, we proposed an effective and simple strategy for the construction of high-performance ROS electrochemical sensor. Noble metal alloy nanoparticles (AuPt nanoparticles) with high catalytic activity were spontaneously coated on the freestanding metallic molybdenum disulfide (MoS) paper independent of any auxiliary conditions. Results have found that the abundant defects and electrons distributed on the metallic MoS paper could provide active sites for the nucleation and growth of noble metal nanoparticles. Besides, the excellent mechanical properties of the MoS paper promote the formation of flexible sensors. The fabricated MoS paper-based sensor was demonstrated to detect ROS with the advantages of wide linear range, prominent selectivity and flexibility, satisfactory detection stability, as well as simple and convenient preparation process. Furthermore, the desirable results obtained in the real sample experiments operated in plant extract pave the way for further real-time monitoring of plant physiological status to provide valuable information for guidance during plant growth.Copyright © 2020 Elsevier B.V. All rights reserved.