In coherent test system like sensing, imaging and communication, the coherence of the light source is very important. Our recent advances focusing on the measurement of noise characterization of highly coherent laser and its applications in the coherent test system are reviewed. Using the noise spectrum and statistic characterization to represent the coherence is proposed. And the parallel 3-step phase-shift measurement method from 500nm to 2000nm based on the 120-degree phase difference fiber interferometer is also proposed to measure the noise characterization. Some kinds of typical highly coherent laser applied in the coherent sensing and imaging system are measured. And the impact of their performance on the application system are also discussed.