A low-threshold middle-infrared (mid-IR) MgO:PPLN optical parametric generation (OPG) pumped by a laser diode (LD) end-pumped Z-type Nd:YLF laser at 1047 nm is realized with high reflectivity(HR) mirror for signal. At repetition rate of 10 kHz, the OPG threshold of 50 'mu'J has been achieved with HR mirror for signal. Compared with the threshold without mirror, the threshold decreases by 17%. Using HR mirror for pump at output side of crystal, the threshold of 40 'mu'J is achieved. The 2.7-4.1 'mu'm continuous tunable output is produced with seven grating periods from 28.5 to 31.5 'mu'm and temperatures from 30 to 200 . When the incident average pump power is 3 W, the OPG idler output power is 0.46 W at 3.26 'mu'm, which corresponds to optical-to-optical conversion efficiency up to 15.3%.