The invention provides a method for preparing 
theabrownin and low-molecular-weight tea polysaccharides by 
solid state 
fermentation of 
green tea as a 
raw material by adopting 
aspergillus niger and 
trametes trogii. The method comprises the following steps: inoculating, performing 
solid state 
fermentation, extracting, performing separation and purification, 
drying and the like. Specifically, the method comprises the following concrete steps: spraying water containing 
aspergillus niger and 
trametes trogii into crushed 
green tea, and fermenting in a room-temperature environment to obtain a fermented material; adding water into the fermented material, performing heating extraction, and filtering extraction liquid through gauze and a 
microfiltration membrane to obtain filter liquor; performing heat 
evaporation concentration or vacuum concentration on the filter liquor, adding an edible 
alcohol aqueous solution into concentrated liquid, fully uniformly mixing, standing, centrifuging, and collecting supernatant and precipitate after 
centrifugation respectively; performing heat 
evaporation concentration or vacuum concentration on the supernatant, filtering through an 
ultrafiltration membrane, and performing spray-
drying or vacuum freeze-
drying on filter liquor to obtain 
solid powder namely 
theabrownin; dissolving precipitate generated after 
centrifugation by using water, and spray-drying or freeze-drying to obtain low-molecular-weight tea polysaccharides.