Abstract: The RG-1model of mercury analyzer is superior in easy operation,disturbance-resistance,low detection limit and high precision.With an application example of the mercury survey method in the water transmission project in Dahuofang,Liaoning Province,some questions are discussed on the sampling position,level,granularity and the testing condition.The testing condition are various for each particular instrument.The actual temperature of specimen decides the release in mercury-release analysis,while the preheated time decides the actual temperature of specimen.Only in the certain experimental conditions,can the testing result reach the demanded standard.The method proves effective in structural reconnaissance.