Abstract: On basis of geometry optics,we designed unstable resonators with Gaussian and super-Gaussian variable reflectance mirrors.The mode equations in the cavity is obtained by FFT expressions so as to be easily solved.The 3-D optic intensity distributions in near and far field,as well as reflecting from reflectors,output mirrors,are numerically calculated.These results can be used as available references for design of unstable resonators with variable reflectance mirrors.