The granite cutting processing using diamond circular saw blades is the most extensive application processing methods. The cutting force is measured at different cutting depth ap, sawing feed rate vf and linear velocity v when the granite is cut by diamond circular saw blade by orthogonal experimental method. And the sawing force empirical formulas relative to these three variables are educed. We can obtain the experimental results as follows. The radial force Fn is greater than the tangent force Ft when ap is smaller than the circular saw blade diameter. The corresponding Fn and Ft are all smaller as the feed rate is greater at the same circular saw blade diameter. The cutting forces increase obviously as the cutting depth increases at the same circular saw blade diameter and feed rate.