A periodically poled lithium niobate (PPLN) optical parametric generator (OPG) pumped by a laser diode (LD)-pumped Q-switched Tm,Ho:GdVO4 laser operated at 2.048 \mum with pump pulse of 25 ns and repetition rate of 10 kHz is reported. A continuous tunable middle-infrared (mid-IR) spectrum of 3.88~4.34 \mum is obtained by changing the crystal temperature from 50 to 124 oC. When the incident pump power is 3 W, the total OPG output power is 95 mW, corresponding to optical conversion efficiency of 3