A compact erbium glass laser for laser ranging is designed and its output characteristics are experimentally studied. Experiment results show that using a 940 nm semiconductor laser pump，when the output power is 12 W，the pump pulse width is 1.6 ms，the passively Q-switched crystal T₀ is 92%，the output mirror reflectivity R is 90%，the output will be the pulse laser of center wavelength 1 535 nm，the pulse width will be 5ns，the single pulse energy will be 502 μJ，the repetition frequency will be 10 Hz. The compact laser structure size can be controlled at 32 mm × 12 mm × 8 mm，weight< 10 g.