The performance, combustion and emission characteristics of diesel engine fuelled with corn stalk pyrolysis biooil/diesel emulsions (CBDEs) with Ce0.7Zr0.3O2 nanoadditive were studied. The density and viscosity of CBDEs increased by 10.7% and 159.3% with increasing bio-oil concentration up to 25%, respectively. Meanwhile, the calorific value was correspondingly reduced by 18.5%. Compared to diesel, a lower specific fuel consumption was achieved with the CBDE fuels at medium and high powers. This was attributed to micro-explosion, which resulted in more thorough splitting of fuel droplets caused by the instantaneous and intense vaporization of water, thereby significantly improving fuel vaporization and combustion process. In addition, the addition of Ce0.7Zr0.3O2 nanoparticles led to reduced ignition delay and rapid oxidation, thus resulting in more complete combustion. The specific fuel consumption of CBDEs first decreased and then increased in correlation to the increased bio-oil content, in which CBDEs with bio-oil proportion of 20% showed the lowest and had the highest fuel saving rate close to 8.4%. By comparison of diesel, the CBDEs with lower bio-oil proportion than 20% reduced CO, HC and smoke emission, which were decreased by reducing bio-oil content. Increasing bio-oil proportion led to the effective reduction of NOx emission.