Abstract: The paper had a brief review on the development history of the intrinsic safe theory and the related standards and introduced the assessment theory of t he non explosion intrinsic safe from the different aspects. The paper discussed the intrinsic safe power applied to protect the circuit and to improve the power.After the s tatement on the current variation rate affected to the intrinsic performances, the paper provided the related new assessment method and the new spark test device nee ded to be further studied.The different type intrinsic safe site bus structure was provided.The paper summarized the redundant power structure of the available intrinsic safe site bus system.In the final, the paper had an outlook on the related study focuses and the study orientation of the intrinsic safe theory and technology.