By using injection-locking technique, we develop a diode-pumped Er∶YAG ceramic single frequency pulsed laser seeded by an Er∶YAG nonplanar ring oscillator (NPRO) laser. The 1645 nm single frequency laser with output energy of 11.45 mJ, pulse width of 174 ns and pulse repetition rate of 200 Hz, is obtained. The corresponding M2-factors are 1.45 and 1.42 in x and y directions, respectively. The full width at half-maximum (FWHM) of the frequency spectrum of the heterodyne beating signal between the pulse and the seed is 2.67 MHz. The result indicates that Er∶YAG ceramics have good performance in generating 1.6 μm lasers. This single-frequency pulsed laser can be employed as the seed of coherent wind lidars and remote sensing lidars in the field of laser lidar.