Prussian blue (PB)-Ti3C2Tx hybrid composites (PB@Ti3C2Tx) with peroxidase-like activity were prepared via a mild and green approach, in which Ti3C2Tx acted as a reducing agent, and the multilayer 2D nanostructure could effectively keep the PB nanoparticles away from aggregation. We fabricated a facile colorimetric biosensor for H2O2 detection to demonstrate the peroxidase-like activity of PB@Ti3C2Tx, and the results indicated favorable linearity of H2O2. The Km app value of PB 6@7 for TMB and H2O2 was 0.0134 mM and 0.162 mM, respectively, which was better than that of horseradish peroxidase (HRP). Moreover, we also fabricated a biosensor by immobilizing acetylcholinesterase (AChE) on the PB@Ti3C2Tx-modified electrode. PB@Ti3C2Tx not only has good biocompatibility for AChE but also can obtain a detectable signal at lower applied potential (from 0.73 to 0.2 V). A good linearity of malathion was obtained in the range from 1.0 x 10(-15) to 1.0 x 10(-9 )M with a detection limit of 1.3 x 10(-16) M.