Abstract: With samples from different stages of pu-erh tea fermentation as experimental material, fungi were isolated and purified.The isolated strains were conducted tea single strain fermentation under ideal condition and inoculated fermentation to screen out a dominant strain capable of increasing tea polysaccharides.The results showed that 22 strains were isolated and purified from pu-erh tea solid-state fermentation, 5 dominant strain used in inoculated fermentation were high frequency in pu-erh tea.During the fermentation by isolated strains, tea polysaccharides increased significantly ( p < 0.05) . Especially in fermentation inoculated by PEZJ-1, tea polysaccharides increased most obviously and reached 23.57% and 27.85% under ideal condition and inoculated fermentation, respectively. Based on the colonial morphology, conidium microscopic characteristics and 18 S r DNA gene sequence, the strain of PEZJ-1 was identified as Aspergillus niger.Therefore, in pu-erh tea solid-state fermentation, exogenous inoculation could improve tea polysaccharides significantly.And Aspergillus niger enhanced tea polysaccharides by a wide margin, which provides the microbial strain for the development of tea polysaccharides.