An efficient and single frequency Er:YAG laser pumped by an MGo:PPLN laser locked at 1532 nm with double F-P etalons was reported. The Er:YAG laser operated at 1645 nm, 550 mW of 1645 nm output was achieved under total incident pump power of 7 W. Using the etalons, 45 mW single frequency 1645.1 nm laser was achieved.