A scanning plasma etching system based on parallel probe actuation was developed to realize micro- and nano-scale etching. The electrical and optical emission spectra of a micro plasma reactor which was a key device in the system were measured to explore the characteristics of the plasma in the reactor. First, a metal-dielectric-metal structure microplasma reactor with an inverted pyramidal hollow cathode was fabricated based on Micro-electric-mechanic System(MEMS) technology. Then,a testing system was set up to measure the V-I curve and optical emission spectra of the microplasma generated at a SF6 gas pressure of 5-12 kPa and drived by a DC mode. Experimental result shows that the discharge current is increased in linearity with the discharge voltage. When the gas pressure increases from 5 kPa to 12 kPa, the discharge current is increased from 2.1~2.82 μA to 3.6~4.2 μA, which means that the microplasma is at an abnormal discharge mode. When the feature size of the reactor decreases from 150 μm to 30 μm, the characteristic line of fluorine(703.7 nm) is increased about 56%, which demonstrates that the plasma density is increased with reducing device sizes. The measurement result of electrical and optical emission spectra of microplasma indicates that the microplasam reactor is suitable for the scanning plasma etching of silicon.