This paper focused on the key technologies of high reliability communication method through a metal wall in theory and experiment based on ultrasonic. The bidirectional reliability data transmission methods are presented. They are the digital amplitude modulation when the data transmits from the external to the inside and the data transmission based on impedance modulation from internal to external. Meanwhile, the weak signalenhanced transmission methods based on the stochastic resonance theory is studied. The reliability of digital signal under noise background is improved. Then an experimental platform to monitoring the internal state with a metal structure is built, and the data transmission characteristic of a temperature sensor in the sealed container is verified. The data transition rate of 4.8 kbit/s is realized, which indicates that the proposed method has a high engineering value.