The invention discloses a functional sustained or 
controlled release fertilizer core based on a bio-based 
adhesive and a preparation method thereof. The bio-based 
adhesive is prepared through the steps that a 
biomass material is subjected to a liquidation reaction, bio-based polyalcohol is prepared, and the bio-based polyalcohol, a chain 
extender, a cross-linking agent and a curing agent are pre-mixed. The bio-based 
adhesive is prepared from regenerative 
biomass resources, dependence on petrification-based raw materials is reduced, good degradability is achieved, and meanwhile the bio-based adhesive is high in adhesive performance, good in 
heat resistance, high in 
water resistance, easy to spray and easy to dry. The functional sustained or 
controlled release fertilizer core prepared basedon the bio-based adhesive is high in 
granulation rate, large in particle strength, excellent in 
moisture absorption resistance, high in 
impact resistance, good in roundness, good in storage and transport performance and especially suitable for a coated sustained or 
controlled release fertilizer production process, the material fluidifying performance can be improved, the specific area of the fertilizer core is reduced, and the 
coating cost of controlled-release fertilizer is greatly reduced.