Abstract: Based on the seismic intensity instrument (SSI) records of Gaoxiong M_S6.8 earthquake in Taiwan, China which occurred on February 6, 2016, we studied the advantage and reliability of SSI used in earthquake early warning (EEW) through the analysis on precision of phase pick, applicability of peak ground motion attenuation relationships and accuracy of earthquake magnitude estimation results. Meanwhile, we also discussed shortcuts and risks of using SSI during the EEW process. The results showed that for SSI stations with near-epicenter and high signal to noise ratio (SNR), the existing phase pick methods are applicable to obtain accurate P phase arrival time. The existing peak ground motion attenuation laws may not fully apply to SSI stations, and a certain risk exists when apply them to SSI station directly. As a result of dense SSI stations layout, a great quantity of useful information may be acquired in a short time, which is very favorable for earthquake magnitude estimation during the EEW process, and magnitude estimation results could have a good accuracy by using existing methods.