Abstract: This paper introduces the experiment research of pressure drop down and bonding strength developing in slurry jellification process during cementing. Through research, the law,characters and its relations effected on pressure drop and bonding strength have been found. In the basis of research work,the critical anti-channeling conditions have been established. For quantity describing pressure balance degree,the concept of pressure balance factor was presented which present a criterion for cementing quality analysis and operation plan. On the basis of mechanism, the anti-channeling and lock water additive has been developed for a degree oil well slurry which make slurry bond in short time, critical bonding time short,volumn expansion slightly and bonding strength high in bonding interface, to prevent water channeling after cementing.