Frequency domain parameters such as bandwidth and response flatness of electro-optical modulator chip are important evaluation indexes to measure the performance of electro-optical modulator chip. The frequency domain parameter testing method of electro-optical modulator chip is studied, and a frequency response parameter testing system of electro-optical modulator chip based on ultra-wide bandwidth lightwave component analyzer is established. The core frequency response parameters of the electro-optical modulator chip are tested in the range of 10 MHz~110 GHz. Experimental results show that the measurement results of the proposed method are in good agreement with the simulation results, and it is an efficient and high-precision method for testing the frequency response parameters of the electro-optical modulator chip.