Abstract: In the paper, the importance of intercropping and relay system to the foodstuff safety was briefly reviewed. And then the authors discussed the key progress in the studies of intercropping and relay system. First, the characteristic of solar radiation utilization of intercropping or relay cropping compound colony was reviewed, which indicated that intercropping and relay cropping system could increase the use efficiency of solar radiation by improving the photosynthesis ability, light capture and transformation. Second, the competition and complementation of nitrogen, phosphor, potassium and water and the mechanisms of higher use efficiency on resources were discussed. Finally, the effects on the yield and quality of each crop in intercropping or relay systems were summarized. Intercropping or relay cropping could increase the total yield by 20%~50%, which was achieved by reasonable planting density and compound colony structure. And the effects of different types intercropping and relay cropping system on qualities, such as the yield and content of protein, crude fiber, crude fat, crude ash and nitrogen free extract of organs and grain, were quite different. It also gave some suggestions to further studies on resources utilization, yield and quality of intercropping and relay cropping system, based on the argumentations above.