Abstract: Making use of cholesteric liquid crystals which change color with temperature, the impingement cooling for an array of 7 10 holes in diameter of 2.4mm with nondimensional hole spacing of x/d=5, y/d= 6.67 was experimentally Investigated. When nondimensional distances z/d between holes with both in-line and staggered arrangement and impinging surface are 1.08, 2.16 and 3.25, the results of thermal visualization show that for the same condition of flow the relative cooling effectiveness of inline arrangement is higher than that of staggered one, and the distance of z/d=2.16 gives the greatest heat tran-sfer effectiveness. The isograms of heat transfer coefficients of impingement cooling are also obtained.