A KeyMod quick mounting arrangement is arranged for detachably coupling an accessory at a firearm having a KeyMod mounting slot, wherein the arrangement includes a mounting body having a first side extended from the accessory to be detachably coupled with the firearm, and a coupling head movably extended from the mounting body between a releasing position and a securing position. The coupling head has a head portion outwardly protruded from an opposed second side of the mounting body, wherein the mounting body is stationary when the coupling head is moved between the releasing position and the securing position. In the releasing position, the head portion of the coupling head is disposed in an enlarged slot portion of the mounting slot. In the securing position, the head portion of the coupling head is slid to a narrower slot portion of the mounting slot for securing the accessory at the firearm.