Parameters identification and complete synchronization between the fractional-order chaotic liu system and the factional-order chaotic system with uncertain parameters are investigated in this paper. Firstly, based on the stability theory a synchronistic controller containing a time-varied gain and an estimating variation is proposed, and the estimating variation is a kind of approaching continually to the true value of the uncertain parameters with time evolution. Secondly, the method of synchronization is proved. Finally, some examples are given for simulation and verification. The simulation results show that the parameters identification and the complete synchronization are realized simultaneously by using this method. Furthermore, the equations are identical and only the parameters are different in the three examples, and the switching synchronization can be realized between liu system and three different chaotic systems by altering partial parameters.