Gravitational waves propagate outward in the form of gravitational radiation. Their interaction with matter is minimal, but they are enough to cause a tiny phase difference of free mass. Ground gravitational wavedetectors are all based on Michelson interferometer. Laser-interferometer gravitational wave detectors are cavity-enhanced Michelson interferometers. Its five-length degree of freedom of the control system is an essential part of the whole interferometer. Measurement of locking matrix and coupling of degrees of freedom help to improve the control system. Laser interferometer for detecting gravitational radiation senses and measures the phase difference of laser through two arms of Michelson interferometer. This phase difference is generated when two beams recombine at the beam splitter, and is converted into observable intensity change through interference. For a given phase difference, the signal response is proportional to the optical power in the interferometer. The final sensitivity of the gravitational wave detector is determined by the signal response and background noise. Theoretically, the detection sensitivity can be improved by increasing the laser power. The signal size can be increased by increasing the total power of the light in the interferometer arm, so we adopted the method of power cycle to improve the sensitivity and measure the frequency response of the interferometer. In the experiment, the interferometer needs continuous monitoring and feedback to keep various parameters at the correct working point. In this paper, we found that the frequency response was enhanced by a factor of 6.15 by adding the power recovery mirror. Considering the loss of the system, this was consistent with the theoretical expectation. The degree of influence between locking signals can be measured by the locking matrix. In our experiment, the common-mode degree of freedom has little influence on the differential-mode error signal, but the differential-mode degree of freedom has a great influence on the common-mode error signal, which may be caused by the feedback of only one arm, which will be improved in the next experiment.