A USB based ExpressCard device having a dimension equal to a standard ExpressCard is disclosed to include an ExpressCard having a circuit board accommodated in an electrically insulative bracket and surrounded by a top cover shell and a bottom cover shell, and a USB3.0 connector mounted in an opening in a front locating shell of the electrically insulative bracket of the ExpressCard and having the rear bonding portions of first and second conducting terminals thereof respectively bonded to respective contacts at the circuit board by SMT (surface mounting technology).