The　deposition　kinetics　of　graphene　oxide　(GO)　onto　poly(ethylene　imine)　(PEI)　layer　was　characterized　in　situ　with　pulsed　streaming　potential　(SP)　measurement,　and　it　was　found　that　the　initial　rate　constant　(k(1))　was　dependent　on　the　size　of　GO　with　same　surface　charge　density　at　a　fixed　concentration　under　controlled　experimental　conditions.　Assuming　the　deposition　was　controlled　by　diffusion　at　the　initial　stage,　k(1)　is　proportional　to　R-h(-2/3),　where　R-h　is　the　hydrodynamic　radius.　By　flushing　a　GO　solution　through　a　capillary　coated　with　PEI,　the　initial　change　rate　of　relative　SP　(dE(r)/dt)　was　obtained　in　20　s　and　k(i)　was　measured　with　five　different　concentrations　in　about　2　min.　Three　GO　samples　of　different　sizes　obtained　from　the　same　batch　of　raw　material　were　characterized　with　pulsed　SP　to　get　ki　values,　and　their　sizes　were　verified　with　atomic　force　microscopy　and　dynamic　light　scattering.　The　experimental　results　are　consistent　with　the　predicted　effects　of　the　size　of　NPs　on　their　deposition　kinetics.