Hepatitis E virus (HEV) is an evolving infectious entity that causes viral hepatitis infections worldwide. Current routine methods of identifying and diagnosing HEV are someway laborious and costly. Based on the biomimicking oxidase-like activity of MnO nanosheets, we designed a label-free, highly sensitive colorimetric sensing technique for HEV detection. The prepared MnO catalyst displays intrinsic biomimicking oxidase-like catalytic activity and efficiently oxidizes the 3,3',5,5'-tetramethylbenzidine (TMB) substrate from colorless to blue colored oxidized TMB (oxTMB) product which can be measured at 652 nm by UV-visible spectrum. When the HEV-DNA was added, DNA adsorbed easily on MnO surface through physical adsorption and electrostatic interaction which hinders the oxidase-like catalytic activity of MnO. Upon the introduction of target, the HEV target DNA binds with its complementary ssDNA on the surface of MnO, the hybridized DNA releases from the surface of MnO, which leads to recovery of oxidase-like catalytic activity of MnO. This strategy was applied to construct a colorimetric technique for HEV detection. The approach works in the linear range of 1 fM-100 nM DNA concentration with the limit of detection (LOD) of 3.26 fM (S/N = 3) and quantitative limit (LOQ) of 36.08 fM. The TMB-MnO platform was highly selective for HEV target DNA detection when compared with potential interferences. Result of serum sample analysis demonstrates that this sensing system can be used for clinical diagnostic applications.