Abstract: The Morris Water maze (MWM) is a widely used device to investigate spatial learning and memory in rodents. Previous studies involving antioxidant showed that spatial learning and memory were improved afforded by dietary antioxidants. The present study aimed at investigating the efficacy of flavonoids from Broussonetia papyrifera on spatial acquisition and probe trial performance in KM mice. 16 young adult male KM mice were randomly separated into 2 groups, a control (CG) and an experimental group (EG). Mice underwent gavage with normal saline (0.9%) and flavonoid-loaded solid lipid nanoparticles (FSLN for short) from B. papyrifera (5 mg/kg/day) with the same volume for 4 weeks, respectively. Then, the MWM test was performed. Our results showed that flavonoids extracted from B. papyrifera significantly augmented the spatial learning and reference memory of mice in the experimental group, which may be ascribed to decreasing the overproduction of free radicals and therefore, retarding oxidative damage. Interestingly, swimming speed of the mice sharply increased latterly albeit there was no difference between the EG and CG. This study also demonstrated that FSLN treatment had no adverse marginal impact on the growth and development of the mice. Collectively, this work indicated that flavonoids from B. papyrifera could improve the spatial learning and reference memory in young adult male KM mice without obvious side effect and be used as potential drug for health care.