[en] The composition, network configuration and system operation condition of Lanzhou earthquake early warning system are introduced in details, and the factors influencing the early warning performance are discussed. Then, in combination of the status quo of system, the key technical indicators are analyzed, and the distribution map of consumed time for earthquake early warning is drawn. The result indicates that the average distance among stations in observation network is large, which casts an obvious influence on the time validity of early warning. Under the set conditions, the radius of blind zone ranges between 30.3 km and 39.2 km, and the early warning time increases as the epicentral distance enlarges. In addition, the radius of blind zone is influenced by the focal depth. Furthermore, influenced by the station distribution and density, the distribution of consumed time for earthquake early warning is extremely uneven and characteristic of obvious regional difference. (paper)