A simple kinetic model of modelling hyperbranched polymerisation involving AB(2) and B-f core monomers is developed and analytical solutions of the model are presented. The number- and weight- average polymerisation degrees can be calculated using the model as functions of polymerisation time or conversion degree. Application of the model is tested for predicting the broadness of molecular size distribution of the hyperbranched polymers obtained by varying the procedures of feeding AB(2) monomer to polymerisation reactor.