The output characteristics of an effic ient end-pumped Nd:YVO 4/KTP laser,along with the effective iintracavity doubling efficiency and losses of a highly-pure KTP crystal,have been investiga ted.A maximum SHG power of 5.85 W was obtained at the incident pump power of 19 W,leading to an optical conversion efficiency of 30.8 %.It was found that the ef fective intracavity doubling efficiency exceeded 70 % in most of the pump power range,and a maximum value of 74.1 % was reached.It was also found that the losse s of the highly-pure KTP crystal were merely 0.007 cm -1.