The hot pressed sintering process of Si–Al alloy is researched and determined in this paper. Researched results show that the optimum process is as follows: the pressure is 30 MPa, the temperature is 520°C and the holding time is 120 min. In addition, the compactness of the specimens is improved, and the microstructure is compacted with the increase in sintering temperature and holding time. However, the compactness does not improve when the sintering pressure is >30 MPa. The grains grow and the α-Al phase infiltrates from the specimens when the sintering temperature is >520°C. The compactness does not increase as the sintering time, and the anomalous growth of grain exist in the specimens while the sintering time is >120 min.