In 2015, PISA and TIMSS are coming up to us together. In this study, the data from PISA and TIMSS are used to investigate that which one is a better indicator of national science and technology (S&T) competitiveness? Number of S & T journal articles (per million people) is used as a measure to represent the national S&T competitiveness. Average IQ of the population, research and development (R&D) expenditure (% of GDP) and number of R&D researchers and technicians which affect the national competitiveness in S&T were also investigated. The study shows that PISA science scores would more significantly indicate national S&T competitiveness than TIMSS. Moreover, the study also shows a strong link between competence in S&T and IQ, research and development expenditure (% of GDP) or number of research and development researchers and technicians. Some possible micro-foundations of these relationships are discussed, and policy implication is clear.