The dynamic oscillation characteristics of a special confocal resonator with G1-0 and G2=0 have been analysed. This resonator shows oscillation characteristics of a Gaussian standing-wave resonator, a critical resonator, and a travelling-wave resonator, respectively, when the direction of the rectilinear-motion equation for the resonator is changed. The method for designing the resonator is proposed. Experimental results are in agreement with theoretical analysis.