To　accurately　grasp　the　distribution　characteristics　of　annulus　temperature　and　pressure　in　variable　pressure　gradients　drilling,　based　on　the　theory　of　flow　and　heat　transfer　of　wellbore　fluid　while　fully　considering　the　heat　and　mass　transfer　of　the　fluid　with　variable　mass　at　the　position　of　separator　and　the　change　of　the　physical　parameters　of　circulating　fluid　with　temperature　and　pressure,　the　paper　establishes　a　model　for　predicting　the　annulus　temperature　and　pressure　in　variable　pressure　gradients　drilling,　uses　a　double-cycle　iterative　algorithm　to　solve　the　model,　and　carries　out　a　study　of　numerical　simulation　for　the　distribution　of　annulus　temperature　and　pressure.　The　results　show　that　compared　with　conventional　drilling,　there　is　an　obvious　inflection　point　on　the　distribution　curves　of　annulus　temperature　and　pressure　in　variable　pressure　gradients　drilling,　and　the　position　of　the　inflection　point　is　consistent　with　that　of　the　separator;　due　to　the　injection　of　the　hollow　spheres　with　low　thermal　conductivity,　the　annular　fluid　temperature　in　in　variable　pressure　gradients　drilling　is　lower　than　that　in　conventional　drilling;　the　position　and　efficiency　of　separator,　density　and　volume　fraction　of　the　injected　hollow　spheres　have　great　impacts　on　the　distribution　of　annulus　pressure　in　variable　pressure　gradients　drilling.　©　2020,　Editorial　Office　of　ACTA　PETROLEI　SINICA.　All　right　reserved.