A slide-in structure (210) inside a cradle set (200) for accommodating a personal digital assistant (PDA) module (10) is disclosed. The slide-in structure comprises a base plate (220), a sliding stand (230) and a pushing arm (240). A connector (204) of the cradle set is fastened to the sliding stand via a circuit board (206). The base plate has a pair of sidewalls (222, 224) and two sliding grooves (226) located on of the sidewalls. The two ends of the sliding stand are inserted into the respective sliding grooves so that the sliding stand is free to move relative to the sliding grooves. The pushing arm is in contact with the sliding stand. The pushing arm resiliently pushes the sliding stand to one side of the sliding grooves and provides a buffering force when the PDA module engages with/disengages from the connector in the cradle set.