Semiconductor laser is one of the very important sources in a variety of modern physics experiments, the measured quantities in quantum precision measurement will be demonstrated to the laser parameters such as amplitude, frequency, and phase, so researching semiconductor laser’s phase noise and amplitude noise is significant in the domain of phase-sensitive amplification and interferometric phase measurement. As an optical cavity to improve beam quality and beam mode, mode-cleaner cavity has important applications in quantum precision measurement, quantum communication, quantum computing, quantum key distribution and gravitational wave detection.The noise conversion functions of phase and amplitude fluctuation of a light beam can be deduced, according to the properties of reflection field and transmission field for the mode-cleaner cavity. The mode-cleaner cavity and the balanced homodyne detection are constructed after locking the laser’s frequency. The balanced homodyne detection measures amplitude noise of reflection field and transmission field, the experimental results show that the amplitude noise of transmission field decreases gradually with the detection frequency, and the noise at the frequency far larger than the linewidth reaches the shot noise limit. Nevertheless, the amplitude noise of the reflection field is far larger than that of the transmission field. As a whole, the amplitude noise also decreases gradually with the detection frequency. Linewidth of mode-cleaner cavity is calculated as 2.5 MHz by transmission spectrum, mode cleaner can be regarded as a low-pass filter under the condition of meeting the resonance in the transmission field, the high-frequency noise is greatly suppressed. In this case, when the detection frequencies range from 0 to 2.5 MHz, the amplitude noise of the transmission field is far larger than the shot noise limit. In the range of detection frequencies from 2.5~20 MHz, the amplitude noise decreases gradually with the increase of the analysis frequency in the transmission field. When the detection frequency is 15 MHz, the amplitude noise of the transmission field reaches the shot noise limit. However, when the detection frequencies range from 0 to 20 MHz, the amplitude noise of the reflection field is far larger than the shot noise limit. On the one hand, the mode-cleaner cavity can be regarded as a high-pass filter in the reflection field, which makes a significant contribution to the results. On the other hand, mode-cleaner cavity can interconvert the phase noise and amplitude noise after reflection or transmission. The amplitude noise of transmission field and reflection field can be calculated theoretically based on the noise conversion functions. By comparing the theoretical results with experimental results, the experimental results are consistent with the theoretical results.The phase noise of semiconductor laser is analyzed by measuring the amplitude noise of the reflection field with on-resonance locking and near-resonance locking. The results indicate that the experimental results are consistent with the theoretical results under the condition of on-resonance locking and near-resonance locking. Thus the research demonstrates that phase noise of semiconductor laser can be measured and evaluated by the noise conversion function. Moreover, this study provides a theoretical basis and provides an important complement for the noise conversion of mode-cleaner cavity. The mode-cleaner cavity is studied from the point of noise conversion in this paper, and the research demonstrates that the experimental results are consistent with the theoretical results in the transmission and reflection field. At the same time, the phase noise of semiconductor laser is measured and evaluated, which promotes the development of quantum precision measurement.