Abstract: The upper and lower volutes of the water turbine are connected with 35CrMo steel bolts. By utilizing the linear relationship between the ultrasonic acoustic-time ratio of 35CrMo steel bolts and axial stress, a 24 channels ultrasonic stress intelligent monitoring system was constructed based on FPGA technology and data algorithms. The system consisted of an ultrasonic instrument, 24 piezoelectric probes, a channel converter, a display and control industrial computer, It can simultaneously detect the real-time elastic stress of 24 bolts, achieving real-time stress measurement. And the actual axial stress was measured using this system, and the results showed that the error could fully meet the engineering requirements.