A serial peripheral interface (SPI) circuit and a display using the same are provided. The SPI circuit includes a mater device and a slave device. A serial data input pin and a serial data output pin of the slave device are both electrically connected to a data input/output pin of the master device. When a read instruction is sent from the master device to the slave device, the master device is set in a read status, and the slave device outputs data to the master device via the serial data output pin in response to the read instruction. When a write instruction is sent from the master device to the slave device, the master device is set in a write status, and writes data to the slave device via the serial data input pin thereof in response to the write instruction.