Physicochemical properties of several different kinds of buckwheat flour were determined with wheat flour as the control. By using international standard methods, the rheological properties of the mixture of buckwheat and wheat flour were studied systematically. The results show that compared with wheat flour, the viscosity of buckwheat flour is high and the β-amylase activity of buckwheat flour is very low. The failing-number value of buckwheat flour is higher than 1 000 s. The distribution of nutritive substance is not uniform in the different positions of the grain. The buckwheat bran is rather nutritive, but the flour from the grain center has better processing qualities. The mixture of buckwheat and wheat flour has better technological properties when the percentage of buckwheat flour is less than 30%.