The invention discloses a network fault detection and repair method based on an SDN architecture. The technical scheme of the method is to build a network system consisting of network equipment, a concentrated management server and a monitoring computer, wherein an agent module is deployed on the network equipment; a business layer module, a network state parameter acquisition and strategy execution module, a fault detection reasoning module, a network state parameter database and an expert knowledge base are installed in the concentrated management server; after the network state parameter acquisition and strategy execution module receives a fault detection command sent by a business layer, the network state parameter acquisition and strategy execution module builds communication with the agent module on a router in parallel, and acquires network state information of different network protocols from the agent module by using a self-adaptive roll polling algorithm; and the fault detection reasoning module performs fault detection and repair. By using the method provided by the invention, a known fault can be accurately positioned, fault detection overheads can also be reduced, and automatic repair of the fault can also be ensured.