The ring laser gyro (RLG) light intensity mode-scanning curve is the basis of the frequency stabilization, and also is the basic characterization of the oscillation characteristics for RLG ring laser and is one of the important signs of the gyro performance. By introducing a new parameter which called mode height, other characteristics of the light intensity mode-scanning curve were described. The mode height of the light intensity mode-scanning curve was the maximum variation of the corresponded light intensity under conditions of one 0.632 8 μm cavity length change, which was a characteristic quantity reflecting the sharpness of the light intensity mode-scanning curve. This characteristic quantity was directly related to the gyro frequency stabilization accuracy and the frequency stabilization response time. The higher the mode height, the higher the corresponding frequency stabilization accuracy, and the shorter the frequency stabilization response time. The physical mechanism of the mode height in RLG scanning process was analyzed theoretically, and the main factors affecting the mode height were determined. Through the theoretical analysis and the numerical simulation, it is concluded that: by increasing the curvature radius of spherical mirror, increasing the cavity length, reducing the loss and increasing the gain, the mode height of the RLG light intensity mode-scanning curve can be increased more than 3 times, which has important guiding significance and practical engineering value for improving the frequency stabilization accuracy, shortening the frequency stabilization response time, reducing the nonlinear error of gyro proportional factor, and improving the fast stability of RLG.