The invention discloses a tool preparing mechanism of a chain tool magazine. The tool preparing mechanism comprises an up-down translation frame and a front-back translation frame. The up-down translation frame is provided with an up-down translation drive mechanism and an up-down translation guide mechanism. The front-back translation frame is provided with a front-back translation drive mechanism, a front-back translation guide mechanism and a tool clamping mechanism. The tool preparing mechanism has the advantages that the tool preparing mechanism is separated from a tool taking and changing mechanism, the weight of a tool magazine moving part can be reduced greatly, tool preparing efficiency of the tool magazine is increased, and the tool changing speed of the tool changing mechanism is increased positively; when the tool preparing mechanism operates, a tool changing jaw pair is in a clamping state during tool pulling, the structure is higher in safety as compared with a tool grabbing arm clamping a tool purely by a spring, and safe and reliable tool preparing of the chain tool magazine is achieved.