An experimental study on heat transfer behaviors of a confined slot jet impingement has been systematically performed. The parametric effects of jet Reynolds numbers and jet separation distance on heat transfer characteristics of the heated target surface are explored. With the measurement of jet mean velocity and turbulence intensity distributions at nozzle exit, two jet Bow characteristics at nozzle exit, initially laminar and transitional/turbulent regimes, are classified. As for the investigation of heat transfer behaviors on stagnation, local and average Nusselt number, it is evident that the effect of jet separation distance is not significant; while the heat transfer performance increases with increasing jet Reynolds number. Comparisons of the present experimental data with the existing numerical and experimental results are made. Besides, two new empirical correlations for stagnation and average Nusselt numbers on the heated target surface are also reported in the study. Furthermore, a concept of effective cooling length is introduced to evaluate the average Nusselt number on a finite-length target surface, the existing numerical results are reasonably consistent with the present experimental data.