A card connector includes an insulating housing defining a receiving chamber, and electrical terminals disposed in the insulating housing. A fool-proofing board has top edges of a front end thereof designed with slopes. Two lifting terminals are disposed in two sides of the receiving chamber with elastic portions thereof projecting upward in the receiving chamber to prop the fool-proofing board over the receiving chamber. Wherein the fool-proofing board can be pressed downward into the receiving chamber by a common SIM card under the guiding of the slopes, or move rearward under the drive of a micro SIM card of which a rear is inserted in the front end of the fool-proofing board. An ejection device is assembled in the insulating housing for ejecting the cards out of the card connector. A shielding shell is covered on the insulating housing.