The invention provides a method for starting a system and a computer system. The method comprises the following steps: setting processors to be in a manageable mode in advance; S1, communicating a physical link of each processor to a south bridge; S2, establishing a route of each processor for accessing the south bridge, and transmitting the corresponding route of each processor to the processor; S3, transmitting a system starting command to each processor, wherein after each processor receives the system starting command, according to the route for accessing the south bridge, each processor can access the south bridge through the corresponding physical link, obtaining a system starting routine, and executing the system starting routine. By means of the method for starting the system and the computer system, the number of the south bridges can be reduced.