The present invention relates to a low-thermal resistance pressing device for a socket, which mainly comprises a housing, an inner collar, a heat conductive pressing block, a bearing collar and a locking member. The locking member on the housing is used to lock the socket. The inner collar is threadedly engaged with the housing. The bearing collar is located between the inner collar and the heat conductive pressing block. In the case of rotating the inner collar in the housing, the bearing collar drives the heat conductive pressing block to move axially so as to exert an axial force to a device to be tested. Because the heat conductive pressing block protrudes from the upper and lower surfaces of the housing, one end thereof can be in contact with a temperature control module, and the other end thereof can be in contact with the device to be tested.