The invention relates to an alga 
microorganism fertilizer agent and a preparation method thereof and belongs to the technical field of aquiculture and the like. The alga 
microorganism fertilizer agent is fermented in such a way that 
monosodium glutamate waste liquid, alga paste, 
photosynthetic bacteria, actinomycetes, azotobacters and 
bacillus subtilis are compounded, and meanwhile, 
chitosan, 
chitosan oligosaccharide, microelements and molasses are added according to appropriate parts. The alga 
microorganism fertilizer agent is formed in such a way that the 
monosodium glutamate waste liquid is adopted for 
fermentation, and the raw 
materials preparation is simple; high-content compound 
bacteria are contained (the content of the 
bacillus subtilis is larger than three hundred million / mL, and the total content of the 
photosynthetic bacteria, the actinomycetes and the azotobacters is larger than one hundred million / mL) and the fertilizing effect is obvious; and the alga microorganism fertilizer agent also has a function of purifying 
water body, has a wide application range, and is suitable for sea-water and fresh-water cultivation.