An M7.4 earthquake occurred in Maduo county, Qinghai Province. the Sichuan Earthquake Early Warning System(EEWS) successfully captured this earthquake and output the early warning results. In this paper, we analyzed the eight early warning processing results and the effectiveness of disaster reduction of this earthquake. the epicenter distance of the earthquake is 55km from the Sichuan Earthquake Early Warning Network(EEWN). the first warning processing result was released 12.19s after the first station was triggered, and the first 5 warning processing results took less than 35s to the triggering time of the first station, which meets the timeliness requirements of early warning. Compared with the official earthquake catalog, the first warning processing results show that the deviation of the epicenter position is 17.1km, the magnitude deviation is -1.8 with the blind zone of 121km. As more stations involved in the calculation, the deviations of both the epicenter position and magnitude are getting smaller and smaller, but the blind zone radius is increasing. Due to the long rupture time of the earthquake and the waveform clipping of the seismic stations, the magnitudes from eight early warning are all smaller than the catalog value.the effective beneficiary area of this earthquake early warning is the circular area with an epicenter distance of 121~324km so that the effectiveness of disaster reduction in this area is remarkable. the results of this earthquake early warning show that the Sichuan EEWS is of a good capability for early warning output in this earthquake outside the Sichuan EEWN, which has an important significant reference for the early warning of large earthquakes outside the earthquake early warning network.