A new type of resonator called telescopic-crossed prism resonator is proposed and investigated on a repetitave YAG laser. Theoretical analyses and experimental rosula have showed that this resonator has a high mechanical stability and excellent transverse mode selectivity even if a YAG rod with moderate optical quality is used. By using this resonator, it is easy to obtain a beam which can give an output power of 10 MW andts divergence angle less than 1 mr.