Because of the non-linear character of the measurement principle,most angle measurement methods based on laser interference techology were used only for the measurement of small angles.In order to enlarge the angle measurement range,a new method which can linearize the principle and realize random angle measurement by interference was proposed here.Two interference systems perpendicular to each other were used to generate two orthogonal signals.The difference between the generaed sine and cosine signals was made as the output and the relation between the measured angle and the output signal is thus approximately linear.Theoretical analysis and experimental verification were made in this paper.Experimental results show that the linearity of the signal is greatly improved and the non-linearity deviation is reduced to one-twentieth.