Abstract: Using compact fluidized bed as calcium cycle biomass gasifier to explore the techo-economic feasibility of synergistic capture of CO₂ and hydrogen production through calcium cycle biomass gasification, thereby achieving negative carbon emissions. Models for zero carbon and negative carbon biomass gasification hydrogen production systems were established, simulation on both systems was conducted, and analysis of economic performance was conducted. Results show that the levelized cost of hydrogen (LCOH) of the compact fluidized bed gasifier is 2.78 and 2.93 /kg under zero carbon and negative carbon emission conditions, respectively. Considering the CO₂ market price, LCOH under negative carbon emission condition can be further reduced to 2.47 /kg. The negative carbon emission biomass hydrogen production system based on compact fluidized bed gasifier not only has lower cost, but also exhibits superior carbon emission reduction potential.