For improving the heat dissipation of heat sink, a porous lattice structure under jet impingement was developed and its flow and heat transfer properties were investigated via simulation and experiments. The effects of its height (4–12 mm), porosity (0.52–0.92) and jet velocity (1–4 m s-1) on the flow and heat transfer characteristics were investigated. Results show that for a given inlet velocity, as the decrease of porosity, the heat transfer is increased, as well as the pressure drop or pump power. For a low pump power case, higher porosity such as 0.82 will be helpful for heat transfer, but lower porosity will be helpful for a high pump power instance. As the increase of height of lattice structure, the Nusselt number increased and subsequently decreased, with an optimal height of 6 mm. The lattice porous structure offers better heat transfer performance with comparison to conventional fin and foam fin heat sinks. At CfRe3 equal to 8.45 × 1012, the Nusselt number of the lattice porous structure is approximately 35% more than the other two structure. Also, Experiments were carried out in this study and experimental results agreed well with the simulated ones.