In this paper, interactions of a combustor wall and film cooling on a vane endwall with two rows of cylindrical holes are numerically investigated. The film cooling holes are located at 0.20 axial chord length upstream of the vane leading edge. A flat plate with a square trailing edge is positioned upstream of the film cooling holes to model the combustor wall. Air with inlet Mach number of 0.17 enters the vane passage, leading to a sonic condition at the passage throat with exit Mach number of about 1.0. Three different axial and clocking positions of the vertical combustor wall model are examined at inlet blowing ratios of 1.3-2.8, respectively. In comparison with the datum clean configuration, the results show that the presence of the combustor wall greatly alters the flowfield in the vane passage and thus the film cooling patterns, particularly near the leading edge stagnation region and the pressure side of the endwall passage. The overall film cooling performance can be more or less improved by the shed vortices from the combustor wall. In addition, the tangential shift of the combustor wall is found to have more prominent effect on the endwall flowfield and film cooling than its axial movement.