Abstract: Results of tests performed on the relationship between transistor "increased rating-rating-derating" PN junction temperature and failure rate are presented, with a view to establishing the prediction formula for transistor base failure rate. The scope of application of the Arrehnius law is studied from the view point of physics of failure. The combining of different kinds of data obtained by China and the obtaining of base failure rate curve of transistors with the regression method are introduced. So are the establishment of base failure rate formula for transistor with the relevant U.S. MIL-HDBKs and the Arrehnius supplementary mathematics model as reference. The verification proves that the prediction made by the base failure rate formula is quite excellent.