Abstract: For applications in coherent optical communications in space and coherent laser detection, the linewidth, noise and tuning characteristics of nonplanar ring lasers were studied systematically in experiment. The output power in single frequency reached 752 mW, with 42% optical-optical efficiency and 54% slope efficiency. The laser linewidth was measured by delayed self -heterodyne interferometry technique. Linewidth decreased with increased pump power. The linewidth was smaller than 1 kHz with output power smaller than 200 mW, and the linewidth was 2.3 kHz at highest output power. Laser intensity noise was mainly attributed to relaxed oscillation. The relative intensity noise (RIN) decreased with increased pump power. The RIN was -93 dB/Hz at 1.78 W pump power. The laser frequency could be tuned by temperature and PZT. Thermal tuning range reached 62 GHz. PZT tuning range was 130 MHz with 100 kHz response bandwidth.