The mixing characteristics of pylon injection in a Scramjet combustor and effects of film cooling to protect pylon from air-heating were investigated. Three-dimensional Navier-Stokes equations with $k-{omega}$ SST turbulence model were used. Fuel hydrogen and air were considered as coolants. There were remarkable improvements of penetration and mixing rate with the pylon injection. There was also over-heating on the front surface of the pylon without film cooling. The coolant injected parallel to the front surface of the pylon protects the pylon from over-heating.