In this study, we construct a high-sensitivity optoacoustic mesoscopy (OPAM) experimental system with a multi-angle scanning mode that can simultaneously perform high-sensitivity measurements and achieve multi-angle information acquisition. This system is employed to acquire the structural and functional information related to small-animal tumor models. The spatial resolution of this OPAM experimental system is verified via a phantom experiment that satisfies the OPAM imaging requirements. Further, by applying the OPAM experimental system on two types of small-animal tumor models, their structural images and obvious type characteristics are presented. Subsequently, the blood oxygen saturation values of the tumors are obtained using the OPAM experimental system under the dual-wavelength measurement condition. The experimental results denote that the OPAM experimental system can provide valuable reference and guidance for oncology research and that the proposed system exhibits considerable application prospects in the field of biomedical research.