The invention discloses a clamping device for a frequency-difference tunable double-frequency microchip laser; the double-frequency microchip laser comprises a crystal group and a light source, wherein the crystal group comprises an attached crystal A and crystal B; the crystal B is an electro-optical crystal, and the two sides of the crystal B are connected with electrodes; the clamping device comprises a base and a crystal shell provided with a clamping mechanism, and the crystal shell is formed by laminating four sheets; a conducting plate B and a conducting plate A are arranged on the outer side for performing heat conduction, and an insulating plate B and an insulating plate A are arranged on the inner side to be used as the clamping mechanism of the crystal shell; a groove a and a groove b are formed in the upper end surface of the base, and the crystal shell is arranged in the groove a; the lower end surface is fixed with a heat sink; a temperature sensor is embedded into the groove b, and the temperature of the clamping device is detected in real time, and the temperature is fed back to a temperature controller; the temperature controller is arranged between the base and the heat sink, and the temperature of the crystal B is adjusted according to the monitored temperature, so that the temperature of the crystal B is within a set temperature range; and a through hole forallowing the light source to pass through is formed in the center of the crystal shell.