This paper presented a self-designed scanning laser optical tomography mesoscopic imaging system based on LabVIEW and explored its capabilities to image intact biological organs or tissues. The system is consisted of an aligned laser, a four dimension translation stage, a scanning mirror and a photomultiplier tube. The spatial resolution of the system is better than 20 μm with an imaging field of 1 cm. The system operation process and preliminary biomedical applications were demonstrated through the 3-D autofluorescence imaging of a mouse lung. Compared to the traditional biomedical optical imaging techniques, scanning laser optical tomography provides the advantages of high photon collection efficiency, large sample range and easy operation.