The present study applies the numerical and inverse methods in conjunction with experimental measured temperatures to estimate the heat transfer coefficient and fin efficiency for the plate-fin heat sink with various fin spacings. Fin temperature, ambient air temperature and air velocity are measured from the present experimental apparatus conducted in a small wind tunnel. Due to the non-uniform distribution of the heat transfer coefficient, the entire fin is divided into several sub-fin regions before performing the numerical inverse scheme. The average heat transfer coefficient in each sub-fin region is assumed to be unknown. Later, the present inverse scheme in conjunction with experimental measured temperatures is applied to determine the heat transfer coefficient and fin efficiency. The heat transfer and fluid flow characteristics are obtained by the commercial software of FLUENT. In order to investigate the accuracy of the heat transfer coefficient, the comparison between the present inverse and numerical results and those obtained from the existing correlations will be made. The calculated temperatures of FLUENT also compare with the experimental fin temperature data at selected measurement locations.