Droplet　generation　in　a　T-junction　with　surfactants　is　simulated　using　our　recently　developed　lattice　Boltzmann　method.　The　method　is　first　used　to　explore　the　effect　of　surfactant　concentration　ψ　b　on　droplet　generation.　As　ψ　b　increases,　droplet　generation　tends　to　shift　from　squeezing　to　dripping　regime　and　then　to　jetting　regime.　In　the　clean　system,　the　upstream　pressure　varies　almost　periodically　with　time.　However,　in　the　surfactant-laden　system,　the　upstream　pressure　no　longer　varies　periodically　but　overall　increases　with　time　for　droplet　generation　in　squeezing　and　dripping　regimes.　This　is　because　the　addition　of　surfactants　results　in　an　additional　pressure　drop　between　the　front　and　rear　of　the　generated　droplet.　Then,　droplet　generation　in　both　clean　and　surfactant-laden　systems　is　compared　to　explore　the　surfactant　role　under　different　values　of　the　capillary　number　C　a.　In　either　clean　or　surfactant-laden　system,　the　pressure　upstream　of　the　junction　rapidly　decreases　as　C　a　increases.　In　the　presence　of　surfactants,　the　upstream　pressure　overall　increases　with　time　for　droplet　generation　in　squeezing　and　dripping　regimes,　but　the　increased　amplitude　decreases　with　C　a.　Finally,　we　establish　the　phase　diagrams　describing　how　the　droplet　generation　regime　varies　with　flow　rate　ratio　and　C　a　in　both　clean　and　surfactant-laden　systems.　It　is　found　that　the　addition　of　surfactants　reduces　the　critical　capillary　number　distinguishing　squeezing　from　dripping　and　the　critical　capillary　number　distinguishing　dripping　from　jetting.　©　2022　Author(s).