Organs maintain their unique functions through a variety of distinctive vessel systems. However, examination of multiset vessels over the entire organ still remains challenging due to the difficulties of assigning multiple vessel systems and labor-intensive imaging reconstruction technologies. Here, an organ-level photoacoustic microscopic imaging platform, named Organ-PAM, with a micron-scale spatial resolution and ultra-large field of view (FOV), which can achieve a lateral and axial FOV of up to ≈81 cm 2 and ≈30 mm, respectively, is presented. With the assistance of whole-organ decellularization, optical clearing, and a specifically designed photoacoustic gradient concentration differential angiographic pipeline, the visualization of up to four sets of vessel systems inside diversified organs is successfully achieved with multiple scales. In addition, quantitative analyses of vessel systems in both healthy livers and kidneys as well as cancerous livers with exogenous transplanted tumors are conducted at different stages. Thus, the platform enables high-efficiency multiset vessel imaging, recognition, and quantification of different organs, providing critical insights into distinct vessel systems under varying pathological conditions.