Microgram weights have a wide range of applications in the mechanical testing of bio-material sensors and nanotechnology market which typically involves the manufacture of objects with dimensions of less than 100 nanometers. Now it is available with a calibration certificate in National Institute of Metrology (China) that customers can be assured of full traceability to the national primary standard of mass, NO.60, which make allow customers with specialized nanotechnology applications to use the weight values range from 0.05 mg to 0.5 mg with standard uncertainty of just 0.3 μg to 0.08μg.In the paper, an effective method was developed to calibrate weights, along with new methods of calculating uncertainties that would satisfy OIML R111 requirements. This new calibration method involved comparing the weights with the 1 mg standard mass standards using a combination of subdivision and substitution weighing scheme.