Under economic globalization, the industrial structure of Taiwan has been greatly changed. Traditional industries are declining, and high-tech industries and service sector are rising. With the expansion of high-tech industries and service sector, when the high-level labor force cannot fully meet the demand, it is required to input high-level labor force from other countries. Therefore, this study mainly analyzes illegal cases of foreign professionals and the reasons behind, and eventually finds out the condition of illegal use of foreign professionals. Violations can be categorized into illegal employment, illegal service, illegal application and illegal use. And there are 8 reasons of violations: nonconforming qualification for application include, speculator’s attitude, the drive of expectation on sons and daughters to be talents, extremely high competition and instability of the market, impact of the kickback strategy, difficult certification of diploma, careless check of documents and blue-collar workers pretending to be white-collar workers.