Experiments are conducted to form dental cobalt chromium alloy part with selective laser melting method. By analyzing microstructure of the specimens, effects that processing parameters of laser power, scan speed, scan space and laser energy density exert on the surface roughness, relative density and hardness of cobalt chromium are studied. Research results show that different laser power, scan speed and spacing lead to different surface roughness although the laser energy density remains the same. Relative density of SLM cobalt- chromium alloy increases as the laser power increases and the rate of change slows down. When scanning speed varies from 80 mm/s to 100 mm/s, maximum value of SLM CoCr part reaches 94.95% . With the increase of laser scanning space, the relative density reduces. Besides, with laser power varying from 50 W to 100 W, net- shaped grain size increases from 0.8 mm to 2 mm, while higher laser power will cause much bigger grain size and decrease the Vickers hardness. The average hardness of SLM CoCr part is 392 HV, slightly higher than the standard value within a reasonable range.