Accurate numerical modeling is prerequisite of predicting plasma behavior and understanding the complex physical and chemical processes in a plasma system. The evolution of nonequilibrium modeling of arcjet to its current state of development is traced, and some uncertainties in the way of further progress are discussed. It is demonstrated that the accuracy of two-temperature plasma transport coefficients can be improved by adopting more reasonable interatomic potentials. A comparison of the chemical kinetic rate coefficients for the same kinetic process shows some discrepancies, which further indicates that there exist some uncertainties on the inelastic cross sections obtained from experimental measurement or theoretic calculation. Application and extension of three-level atomic model of argon in nonequilibrium modeling are briefly reviewed, and the criteria required in the choice of chemical kinetic processes are discussed. The elementary processes involved in high velocity plasma flow can be investigated by collisional radiative model (CR model). The method of applying CR model on the analysis of nonequilibrium plasma processes in arcjet is presented as an example in some detail.