Capacitive power transfer(CPT) technology is a newly emerging research focus for EV charging applications. Due to the absence of eddy current loss and light weight of the capacitive coupling metal plates, CPT technology is considered to be a promising alternative to the inductive power transfer(IPT) technology. However, the parameter identification of the CPT system has not been well studied. In this paper, a multi-parameter identification method based on spectral information is proposed, which based on rational fractional fitting algorithm and network synthesis theory. By adding some known parameters to this method, the parameter identification algorithm under constraint is proposed to improve the noise tolerance of the identification results, and at the same time, it can also have better identification accuracy. The experimental results show that the parameter identification algorithm based on spectrum information can effectively identify the parameters of the circuit model of the CPT system, and the identification accuracy is less than 10%.