A conductively cooled, laser diode (LD) end-pumped, injection-seeded single frequency Nd:YAG laser is designed and implemented. The laser utilizes Nd:YAG rod as gain medium and compact dual-end-pumping arrangement using two fiber-coupled LDs with a maximum output of 150 W. The optimized ramp-fire technique is applied to build reliable single longitudinal mode oscillating. The laser is capable of producing a 10-mJ Q-switched pulse with 13-ns pulse width at 1064 nm at a pulse repetition rate of 250 Hz. The output beam qualities M2 of approximately 1.19 and 1.22 in horizontal and vertical directions are detected, respectively.