Abstract: In the cementing of conductor and surface casing,cement slurry has long waiting on cement (WOC) time due to the low bottom hole circulating temperature(BHCT),the slowly increasing compressive strength of cement,the drilling cost has been increased,the annular gas channeling would occur,which impairs cementing quality and operation safety.In view of the fact that there are few types of early strength agents currently at home ,some early strength agents have poor effectiveness and significant negative impact on slurry rheology etc,a new compound early strength agent with no chlorine and containing crystal seed was selected by laboratory tests.The thickening time,compressive strength,rheologic properties,anti-gas channeling ability and other parameters of the slurry have been tested.The results showed that the cement slurry has such advantages as right-angle setting behavior,short WOC time at low temperature,high early strength,good rheologic properties,strong ability of anti-gas channeling,etc.The low density cement slurry ranged from 1.30 to 1.90 g/cm3,provides a reliable and safe cementing operation in shallow wells at low-temperature and different reservoir pressures.