On the basis of the assumption of local thermodynamic equilibrium and isothermal spheres, the continuum emission (recombination radiation and bremsstrahlung) and line emission of argon plasmas are investigated. Net emission coefficients are calculated for the argon plasmas in the wavelength ranges of the entire, vacuum ultraviolet and non-vacuum ultraviolet spectra at 0.1 MPa and the temperature range from 5000 K to 25000 K with different sphere radii of Rp. Special attention is paid to analyze the contribution of the vacuum ultraviolet to the entire emission and the influence of various radiative mechanisms on vacuum ultraviolet. The results show that for Rp=0 mm (without self-absorption), the contribution of the vacuum ultraviolet is greater than 94.8%, with the line emission dominant in the radiation. For Rp=1 mm, the contribution decreases due to the strong absorption of the vacuum ultraviolet, accompanied by the improved influence of atomic continuum. Nevertheless, the contribution is still greater than 80% at temperature above 17000 K. Our calculation results are proved to be correct by comparing with the previous calculated and experimental results.