Scanning device and scanning method of large-size projective-capacitance touch screen

The invention discloses a scanning device of a large-size projective-capacitance touch screen, which comprises a group of X-axis slave chips, a group of Y-axis slave chips and a master chip, wherein the master chip is connected to the X-axis slave chips and the Y-axis slave chips, and a synchronizing pin of the master chip is connected to synchronizing pins of the X-axis slave chips and the Y-axis slave chips; a group of interrupt pins of the master pin are respectively connected to interrupt pins of the X-axis slave chips and the Y-axis slave chips. The synchronizing pin of the master chip generates a falling edge synchronizing signal, and the synchronizing pins of the X-axis slave chips and the Y-axis slave chips receive the falling edge synchronizing signal to scan sensors connected with the slave chips so as to obtain scanning data; then the interrupt pins of the slave chips generate a low signal, the interrupt pins corresponding to the master chip receive the low signal, and the master chip is in data co