Observation network of ground fluid in northwestern China is comprehensively evaluated as three stages, that is, establishment, adjustment and development. The observation network of ground fluid has already tended to ripe and makes a certain effect in seismologic surveillance and earthquake prediction.But because it is restricted by some conditions, the network action is still limited. Efficacy of seismologic surveillance of the network is synthetically evaluated. The result shows that medium short term anomalies are observed at sensitive sites in distant field and short impending anomalies are observed at sensitive sites in close field.