Based on poor Brinell hardness measurement information, a novel uncertainty evaluation method was described. According to analyzing the data of all error sources or the limited measurement results, characteristics of these data were gained. And then, by big sample random simulations, sample space of these data can be expanded. Finally, in terms of the Bessel formula and the uncertainty synthesis principle, poor information Brinell hardness measurement uncertainty can be evaluated rightfully. By a practical Brinell hardness measurement, the validity of proposed method was proved.