To explore the effect of Fuling for invigorating spleen and promoting the water metabolism in the rat model with the water and dampness retention caused by spleen deficiency so as to explore its effective substances.Methods:The optimized methods of improper diet and overstrain were used to replicate spleen-deficiency model.The rats with spleen deficiency were further administered intraperitoneal (i.p.) water to prepare the cohesion model of water and dampness.The changes of the rectal temperature，weight，the apparent situation and concentration of D-xylose in urine of rats was used to evaluate the spleen deficiency animal model.The water ratio of faeces，the TP，ALB，TC，HDL-C and LDL-C in serum，AQP1 in the renal medullary part and GAS as the main indexes in the spleen deficiency model with cohesion of water and dampness to elucidate the effective fraction of Fuling.Results:During the period of model preparation,the rats weight was decreased and no change was observed in rectal temperature，indicating that spleen deficiency of rats has been formed.The 7.5 g/kg dose of the water decoction of Fuling was tested as effective dosage.The water decoction，ethyl acetate fraction (EAF) and crude polysaccharide fraction (CPF) could obviously increase the weight of rats with spleen deficiency.Except alcohol eluate fraction (AEF)，the other fractions of Fuling could increase the level of ALB in serum of rats with spleen deficiency significantly.CPF could decrease the level of AQP1 in renal medullary part of rats with spleen deficiency.EAF and CPF could promote the GAS level in serum of rats with spleen deficiency.EAF could increase the loss rates of body weight and the volume of urine of spleen deficiency rats with cohesion of water and dampness.Conclusion:The promoting action of Fuling on water metabolism is mainly via its diuretic function.EAF and CPF are the effective fractions of Fuling for invigorating spleen and EAF is also the effective fraction of Fuling for removing dampness.Consequently，the EAF mainly composed of triterpenoids and CPF might be the effective substances for the sweet flavor of Fuling and EAF might be the effective substances for the pale flavor of Fuling.