First-principles plan-wave pseudopotential method is used to calculate the energy bandgap properties, bowing parameters and structural properties of wurtzite BexZn1-xO alloys. The results show that the energy bandgaps and bowing parameters of BexZn1-xO alloys increase with Be content increasing. We find the energy bandgaps corrected of BexZn1-xO alloys to be in accordance with the experimental value. The reason about the energy bandgap broadening is also analyzed. The average bowing parameter of BexZn1-xO alloys is 6.02 eV, which is in good agreement with previous experimental result. The bowing parameter mostly arises from volume deformation of alloy and charge transfer effect. Futhermore, we analyze the changes of lattice parameter, average bond length and average second-neighboring distance with Be content in BexZn1-xO alloys.