Abstract: Rhizosphere is the densely populated area of the soil where plant roots must compete with invading root systems of neighboring plants and soil-borne microorganisms including bacteria,fungi and insects that feed on organic materials for space,water,and mineral nutrients. Interactions within the rhizosphere are based on complex exchanges involving surrounding plant roots and are highly influenced by edaphic factors. However,below-ground biological interactions that are driven by root exudates are more complex than above-ground interactions. Increasing evidence suggests that root exudates act as information transmitter in the interaction process between plants and their environment and thus play an important active role in root-root and root-microbe communication. In this paper, previous studies are vividly reviewed and the direction of future research disscused.