The invention relates to a clamping device, and specifically discloses an assembly fixture for the head of an embroidery machine. The assembly fixture at least comprises a base and a main body, wherein the base is fixedly connected with the main body; two cantilevers are arranged at the two sides of one end away from the base, of the main body; the two cantilevers are connected with the main body through two first connection sheets respectively; a second connection sheet is arranged between the two first connection sheets; one end of the second connection sheet is connected with the main body; a first location thread hole is arranged in the other end of the second connection sheet; the main body is provided with at least one second location thread hole between the two cantilevers; a guide rail groove is arranged in one end away from the main body, of each cantilever; each cantilever is provided with at least one guide rail location screw in a manner of being vertical to the corresponding guide rail groove; and each cantilever is provided with a shaft hole along the horizontal direction. The abovementioned device realizes safe and reliable clamping and fixing for the parts of the head, and greatly increases assembly efficiency and improves location accuracy.