In this study, the entropy generation and the heat transfer of pulsating air flow in a horizontal channel with an open cavity heated from below with uniform temperature distribution are numerically investigated. A numerical method based on finite volume method is used to discretize the goving equations. At the inlet of the channel, pulsating velocity is imposed for a range of Strouhal numberspSt from 0 to 1 and amplitudeAp from 0 to 0.5. The effects of the goving parameters, such as frequency and amplitude of the pulsation, Richardson number,Ri, and aspect ratio of the cavity,L/H, on the flow field, temperature distribution, average Nusselt number and average entropy generation, are numerically analyzed. The results indicate that the heat transfer and entropy generation are strongly affected by the frequency and amplitude of the pulsation and this depends on the Richardson number and aspect ratio of the cavity. The pulsation is more effective with the aspect ratio of the cavityL/H=1.5 in terms of heat transfer enhancement and entropy generation minimization.