The kinetic model of chain extension reaction between bisoxazoline and carboxyl group was founded and modified to fit the real experimental results. By the Runge-Kutta numerical method

not only has the change of reaction conversion with time been clearly revealed

but also the key factors that mainly influence the chain extension have been easily tested．The ideal linear model of chain extension accords to a large extent with the former period of the reaction. However

it cannot illustrate the “degradation” in the latter period due to the thermal unstability of products．Modified linear model gives more congruent results．During the whole period of the reaction

the reaction rate constant k and ratio of both reactants r are the key factors. The changes of reaction conditions

such as temperature and chain extender dosage

are simulated easily by varying the value of k and r．Considering the diffusibility in the polymer melt with high viscosity

the distinction of coupling effect of BOZ and PBO can be explained．No other than the same reason

the analysis could only be kept in the qualitative stage at present．