To construct a flow reactor system, which enables to simulate the chemical evolution of biopolymers in an open system in the thermodynamic sense, the influence of stepwise addition of the 2-methylimidazolide of guanosine 5’-monophosphate (2MeImpG) to the template-directed formation of oligoguanylate (oligoG) on polycytidylic acid (polyC) template (TD reaction) was investigated. Both the experiment and the computational simulation of the addition of 2MeImpG showed that the higher oligoGs were accumulated by the addition of 2MeImpG. In addition, the elongation of oligoG was slightly effective when the activated nucleotide monomer was added within a shorter interval period, where the total amount of the addition of the activated monomer was kept as constant. This fact indicates that the continuous supplement of 2MeImpG would facilitate the formation of oligoG rather than the stepwise addition of 2MeImpG when the total amount of guanosine unit was increased. The present study showed that the computer simulations concerning the TD reaction can be used to evaluate experimental data of the TD reaction.