A tool positioning and holding mechanism includes a mounting frame, a feed member, a tool support, a positioning member, an elastic member, and a blocking member. The feed member is slidably mounted on the mounting frame. The tool support is fixed on the feed member and defines a receiving hole to receive the tool. The positioning member is pivotally coupled to the tool support and partially received in the tool support. The elastic member is located between the positioning member and the tool support. The blocking member is fixed on the mounting frame and includes a pushing portion configured to resist the positioning member. The feed member can move the positioning member to allow detachment of the positioning member from the pushing portion, and upon detachment of the positioning member, the positioning member is configured to rotate under an elastic force of the elastic member to position the tool.