Abstract: In view of the respective strength and weakness of the statistical method and rule governed method,a kind of English part of speech tagger based on a cascade of Viterbi and FTBL algorithms is proposed.Its design idea and realization process are discussed.This cascade method views the FTBL algorithm as its whole algorithm,applying Viterbi algorithm to its initialization process during its two phases——rule learning and final tagging.The results show that this method excels either of the separate algorithms,achieving high accuracy of over 98%,and validates the mainstream design idea as a combination of statistical and rule governed methods in natural language processing.