In this work, we design a three-dimensional (3D) strongly-coupled polyaniline/crosslinked carbon nanosheets (PANI/CCNs) composite using a facile in-situ chemical polymerization method. The PANI is uniformly and conformally covered on the thin graphene-like biomass-derived CCNs. The interconnected CCNs with high surface area and electrical conductivity can expose more active sites of PANI and enhance the interfacial electron transfer, which contributes to the improvement of specific capacitance and rate performance. The sheets-like PANI can introduce pseudocapacitance through the surface redox reactions on the surface. As a result, the PANI/ CCNs composite electrode can reach high specific capacitance of 444 and 340 F g(-1) at current densities of 0.1 and 5 A g(-1), respectively. The assembled PANI/CCNs//PANI/CCNs symmetric supercapacitor can reach a high specific capacitance of 72.0 F g(-1) at a current density of 0.1 A g(-1). Moreover, the PANI/CCNs//PANI/CCNs symmetric cell exhibits a high energy density of 28.9 Wh kg(-1) at a power density of 85.1 W kg(-1), which is competitive in the aqueous PANI-based symmetric supercapacitors.