With　two　sets　of　standing-wave　fields　built　in　a　thermal　rubidium　vapor　cell,　we　have　established　a　controllable　photonic　crystal　with　periodic　gain　in　a　coherently　prepared　N-type　four-level　atomic　configuration.　First,　the　photonic　lattice　constructed　by　a　resonant　standing-wave　coupling　field　results　in　a　spatially　modulated　susceptibility　and　makes　the　signal　field　diffract　in　a　discrete　manner　under　the　condition　of　electromagnetically　induced　transparency.　Then,　with　the　addition　of　the　standing-wave　pump　field,　the　N-type　atomic　medium　can　induce　a　periodic　Raman　gain　on　the　signal　field,　which　can　be　effectively　controlled　by　tuning　the　pertinent　atomic　parameters.　The　experimental　demonstration　of　such　a　real-time　reconfigurable　photonic　crystal　structure　with　periodic　Raman　gain　can　pave　the　way　for　realizing　desired　applications　predicted　in　the　gain-modulated　periodic　optical　systems.　(C)　2018　Optical　Society　of　America