Abstract: In order to improve the stability of biomass-based carbon aerogels, lignin(L) was modified with phosphoric acid to obtain phosphinized lignin(PL). Then, a stable covalent bond was formed with bacterial cellulose(BC) to prepare biomass-based carbon aerogels, namely bacterial cellulose/phosphinized lignin(BC/PL) carbon aerogels, which were used as electrodes for supercapacitors. The results showed that with the introduction of phosphoric acid, the thermal stability of the prepared biomass-based carbon aerogels was improved. Meanwhile, XRD analysis and Raman spectroscopy showed that its structural order was similar to the graphite structure, and the specific surface area was 310.9 m²/g, with an average pore size of 2.3 nm. The results of electrochemical performance analysis showed that the prepared modified aerogel had excellent electrochemical performance, with a specific capacity of 216.4 F/g at a current density of 1 A/g and a maximum energy density of 24.4 W·h/kg at a power density of 800 W/kg.