A laser diode dual-end-pumped injection-seeded single-frequency Q-switched double-pulse Nd:YAG laser is designed using a modified ramp-fire technique. The laser is capable of producing a pair of Q-switched single-frequency 1064 nm laser pulses in one pump period. Every pulse has an output energy of up to 10 mJ, width of nearly 20 ns, and interval of about 200 μs between two Q-switched pulses. The optical-to-optical efficiency of this laser is about 22.4% and its slope efficiency is 28%. A narrow spectrum linewidth of less than 28.6 MHz with a frequency of jitter around 1 MHz over 2 min may be obtained, and a beam quality of 1.23 in the horizontal direction and 1.31 in the vertical direction is detected.