Abstract: Reasonable intercropping is a natural barrier against plant disease epidemic. In recent years, using intercropping to control crop diseases has risen to become one of the most important issues in agriculture. Previous studies have mainly focused on field crop collocation patterns, efficient utilization of light, heat and nutrient resources, effects of disease control, and yield advantage. So far, the mechanism of disease control has been rarely summarized systematically. In this review, the control effect of intercropping on airborne and soilborne diseases were summarized first and then the mechanism of intercropping control of diseases, including host crop resistance, pathogens and environment (such as soil condition and canopy microclimate) were demonstrated. The mechanisms of disease suppression mainly include: (1) Nutrient absorption and utilization are promoted and the physiology and biochemistry characteristics of host crops are improved, and thus the resistance of crops to pathogens is increased by reasonable intercropping. (2) On one hand, the diversity of aboveground crops are increased by intercropping and thus physical barrier is formed to block pathogen spread; on the other hand, the increased diversity of root exudates in intercropping systems directly allelopathically inhibit the growth of pathogens and reduce their survival and infection further. (3) The field microclimates (such as temperature, moisture and ventilation conditions) and the soil microecological environment (such as rhizosphere microflora, community structure and diversity as well as soil enzyme activities) are improved to enhance the disease control effect by intercropping. Finally, the limitations of research methods of crop disease control in intercropping systems were discussed and some research prospects in the future were also put forward.