A serial transmission control system accesses data based on status signal, includes a timing register for storing a predetermined times of a basic period width and a predetermined number of trigger times, a data buffer for storing data, a timing control state machine for outputting the status signal until receiving a terminal signal. The status signals have a period width complying with the predetermined time of the basic period width. While the terminal signal is received and a number of outputting the status signals does not comply with the predetermined number of trigger times, the status signal will keep outputting until complying with the predetermined number of trigger times. A transforming circuit is for accessing the data stored in the data buffer.