By constructing a response system, which has the same structure as the parameters-unknown drive system, a parametric adaptive control algorithm is adopted to obtain the synchronization. When the synchronization is achieved, the parameters of the response system are in good agreement with those of the drive system, and the parametric adaptive control low will automatically disappear at the same time. As a consequence, the parameters of the drive system are readily to be determined. Rossler system is used as an example for detailed description. Numerical simulations show the feasibility of the proposed control strategy.