As one of the most economically developed and seismically active regions of China, Fujian faces a threat from severe earthquakes, particularly those that occur in Taiwan. Following the worldwide construction of an earthquake early warning (EEW) system, we developed an EEW system in Fujian in 2009 and began online testing in November 2012. During this testing, our EEW system successfully processed several earthquakes in both the Fujian region and Taiwan. The results showed that, for inland events (Fujian region), the first alarm was generated 6.4±0.97 s after the first station was triggered, with a location error of 4.6±4.0 km and magnitude estimation error of 0.6±0.5. For offshore events (Taiwan), the first alarm was generated 13.7±2.9 s after the first station was triggered, with a location error of 30.6±31.4 km and magnitude estimation error of −0.2±0.4. Online testing allows us to continuously improve and perfect our system. In 2017, our system will officially begin providing EEW information to the public in the Fujian region. In addition to the preceding, the architecture, key algorithms, software design, and online testing results are included in this article to provide readers with a comprehensive understanding of our EEW system.