Abstract: For fast measuring moisture content of tobacco leaves by DC bridges, there are some key factors, i.e., selecting bridge type and position of probe, reducing capacitance influence and non linearity on affecting the accuracy. In this paper, the factors are discussed and a instrument for fast measure moisture content of tobacco leaves is studied and developed by DC bridges. The results of experiments and application show that the instrument needs about 15 seconds for measuring moisture content of tobacco leaves , its measuring range is 8 %～25 % (humid group) , measuring accuracy is - 0. 6 %～0. 6 %. It can meet the demands for measuring moisture content during purchasing and drying of tobacco leaves.