During start-up or grade-change operation of a continuous polymerization reactor, the transition time, required to reach the desired steady state from the initial state, decides the amount of off-specification polymer product which causes treatment problems. It is very important to calculate the minimum transition time and subsequently determine optimal control input trajectories. Due to complex reaction mechanism and highly nonlinear dynamics, however, this time-optimal control problem for a continuous copolymerization reaction during start-up or grade-change operation has been a challenging problem. We propose two level hierarchical time-optimal control methodology that is based on the discretization of transition time interval and application of genetic algorithms combined with heuristic constraints. The proposed methodology has shown better performance than IDP or SQP in terms of accuracy and efficiency. The methodology is illustrated by the application to the time-optimal control problem of continuous MMA-VA copolymerization to produce polymer with a desired molecular weight and composition of VA in a dead copolymer.