Laser communication system needs evaluation and quantitative analysis and it has multiple criteria. In consideration of the fuzziness, diversity and relativity of evaluation criteria, the grey cluster method in grey system theory was introduced to evaluate laser communication system quantitatively. Firstly, the evaluation criteria with fuzziness and relativity were whitened, and then all the laser communication systems were clustered by clustering criteria and the integrated clustering effects of all the criteria of each laser communication system were computed. Finally, the performance evaluation was done through determination of systems’ clustering type. This method can convert a Multiple Criteria Decision Making (MCDM) problem into a Single Criterion Decision Making (SCDM) problem and it is a new method to evaluate laser communication system quantitatively.