Abstract: Combining the development and utilization of bioenergy with carbon capture, utilization and storage（BECCUS） is one of the important methods to reduce CO₂ emissions in the energy field as it can achieve the negative carbon emissions. Biomass ash（BA） generated from the direct combustion of biomass, can be used to absorb and sequestrate CO₂ permanently. However, the issue adopting biomass ash to achieve the negative carbon emissions should be investigated carefully. CO₂ mineralization performance of biomass ash from atmospheric CO₂ and CO₂-rich gas streams with a moderate（101.3 kPa） and high CO₂ partial pressure（300～1 400 kPa） was experimented in terms of CO₂ sequestration capacity. Moreover, negative carbon emissions of these three mineralization pathways were evaluated as well. Results showed that among all the three pathways, the lowest CO₂ sequestration capacity with 60.66 g/kg after 40 days was acquired when CO₂ came from atmosphere. Comparatively, when the initial CO₂ partial pressure was elevated to about 101.3 kPa（i.e., the moderate CO₂ partial pressure case）, the maximum CO₂ sequestration capacity of 121.68 g/kg can be achieved. When CO₂ partial pressure was increased to about 1 400 kPa（i.e., the high CO₂ partial pressure case）, a CO₂ sequestration capacity of 216.85 g/kg was obtained. The actual negative carbon emissions of three mineralization pathways of biomass ash were assessed by comparing CO₂ emissions reduction ascribed to CO₂ sequestration of biomass ash and CO₂ emissions related to energy consumption in the mineralization process and biomass ash transportation. When the transportation distance of biomass ash was less than 207 km, adopting this mineralization pathway in which CO₂ came from the CO₂-rich gas streams with a moderate CO₂ partial pressure（101.3 kPa） might be reasonable for achieving a highest negative carbon emission. When the transportation distance was above 207 km, the pathway in which CO₂ came from the gases with a high CO₂ partial pressure should be sensible.