The service sector plays a key role to employment growth and increased public well-being in OECD countries. The service industries contributed more than 63% of GDP in 2016 and have become the core of economy in Taiwan. Within the service sectors, knowledge-intensive business services (KIBS) particularly illustrate higher levels of productivity and profitability. Moreover, due to lack of the clear measurements of the knowledge intensity with prior investigations in KIBS, the aim of this article is to explore the knowledge intensity of Taiwan's KIBS. This study then further probes into the relationship between knowledge intensity and economic performance. Panel data from 13 service sectors in Taiwan during the period 2007-2015 is analysed with a fixed effect model. This empirical research shows four findings: first, 13 industries are classified into three groups as high, low, and no level of knowledge intensity; second, most of the level of knowledge intensity has been increased from stage one to stage two; third, education level and vocational training rate positively influence productivity; and, finally, the percentage of knowledge workers and vocational training rate have a positive effect on the margin rate.