Abstract:According to the deficiency of the evidence in criminal trial, based on low power series of consumption SCMSTM32L series, this paper designs and implements criminal interrogation heart rate detection system with strong practicability. Whether the things confessed by the criminal are true or false is judged by heart rate change and this method can be regarded as criminal interrogation detection scheme. This paper introduces the overall design of the system in detail, systematic hardware design and systematic software design, finally uses LCD to display the results, implements realtime, continuous and reliable heart rate detection and demonstrates the good application prospect of this system in criminal interrogation field.