Bidirectional reflectance distribution function (BRDF) is an important reflective parameter of object surface. In many measurement systems, the value is achieved in a bow-liked mechanism which simulates the hemi-sphere space, and the incident illuminance and reflect luminance are measured respectively. To raise the uncertainty of BRDF value measuring, a new BRDF absolute value realization system is established. All factors which should be measured are translated to one factor in theory. In structure design, the movement of light source and detector are reduced indeed. The realization of angles for measurement depends on the rotation of sample in multi-dimension. This design is fit for BRDF absolute measurement and it improves the uncertainty.