Abstract: SiC/SiC composites have been widely used in aircraft engines, and resistance to oxidation and corrosion. Nanosecond pulsed lasers offer high material removal rate with relatively low thermal damage; however, when processing SiC/SiC composites, thermal effects such as molten deposition and heat-affected zones (HAZ) can still occur. The machining characteristics of SiC/SiC composites using nanosecond pulsed laser in a static water environment are investigated. Experiments involving grooving and ring-scanning were conducted in two distinct environments, namely in air and static water environments. The effects of parameters such as laser power, repetition frequency, and scan spacing on the processing results were analyzed. The results showed that laser processing assisted by a static water environment can effectively suppress thermal damage, enhance processing localization, and eliminate molten material deposition and HAZ. The groove width increases with the laser power, and is 20%–30% smaller than that processed in air. The groove width decreases with the increasing pulse repetition frequency, and is 40%–79% smaller than that processed in air. There is no deposition or obvious HAZ found in water environment machining.