An ultrasonic in-situ automatic detection system for creep cracks on an inner wall of a hydrogen production furnace tube. The system comprises a computer, a multi-channel ultrasonic system control circuit, a motor driver board, a coreless motor, and a tube crawling machine. Multi-channel piezoelectric transducers are arranged in a circumferential direction of the furnace tube. The computer is configured to send detection instructions to the multi-channel ultrasonic system control circuit through a wireless network; the multi-channel ultrasonic system control circuit is configured to control multiple channels to simultaneously excite the piezoelectric transducers, receive echo signals from the piezoelectric transducers and then send the echo signals back to the computer in a wireless mode; and the motor driver board is configured to drive the coreless motor to drive the tube crawling machine to move, receive motion parameters fed back by motor encoders, and send the motion parameters back to the computer.