Anharmonic lattice dynamics method is employed to investigate the phonon frequency and relaxation time without any fitting parameters. The phonon relaxation time is used in Boltzmann transport equation to predict the lattice thermal conductivity of solid argon between 10 K and 80 K, and the results agree very well with experimental data. The effects of calculation parameters on the prediction accuracy are also analyzed, including mesh size of the reciprocal lattice points, and the broadening factor of delta function. The contribution of each individual phonon mode to the thermal conductivity is investigated. It is found that higher frequency phonons contribute more to the thermal conductivity at higher temperature, which is consistent with previous theoretical results.