Orthorhombic LiMnO2 (o-LiMnO2) are synthesized by hydrothermal technique. Two samples were obtained which crystallize in orthorhombic structure with space group Pmnm. From rietveld refinements，the samples exhibit respectively a spot of cationic disorder on the lithium and manganese sites 4% and 8%，which，however，has no great influence on the magnetism. We have investigated the static and dynamical response of clusters in o-LiMnO2 oxide，and a sequenceof transformations of magnetic states，i.e. antiferromagnetic to ferromagnetic state at T≤TC≈118K and ferromagnetic to canted spin glass state at T≤Tf≈50K are observed.