The　cooperation　of　multiple　Unmanned　Aerial　Vehicles　(UAVs)　has　become　a　promising　sce-nario　in　Space-Air-Ground　Integrated　Networks　(SA-GINs)　recently　due　to　their　widespread　applications,where　wireless　communication　is　a　basic　necessity　and　is　normally　categorized　into　control　and　non-payload　communication　(CNPC)　as　well　as　payload　communication.In　this　paper,we　attempt　to　tackle　two　challenges　of　UAV　communication　respectively　on　establishing　reliable　CNPC　links　against　the　high　mobility　of　UAVs　as　well　as　changeable　communi-cation　conditions,and　on　offering　dynamic　resource　optimization　for　Quality-of-Service　(QoS)　guaranteed　payload　communication　with　variable　link　connectiv-ity.Firstly,we　propose　the　concept　of　air　control-ling　center　(ACC),a　virtual　application　equipped　on　the　infrastructure　in　SAGINs,which　can　collect　global　information　for　estimating　UAV　trajectory　and　com-munication　channels.We　then　introduce　the　knap-sack　problem　for　modelling　resource　optimization　of　UAV　communication　in　order　to　provide　optimal　ac-cess　points　for　both　CNPC　and　payload　communica-tion.Meanwhile,using　the　air　controlling　informa-tion,predictive　decision　algorithm　and　handover　strat-egy　are　introduced　for　the　reliable　connection　with　multiple　access　points.Simulation　results　demonstrate　that　our　proposal　ensures　an　approximate　always-on　reliable　accessing　of　communication　links　and　out-performs　the　existing　methods　against　high　mobility,sparse　distribution,and　physical　obstacles.