An automatic network management method based on an SNMP and a stochastic Petri net belongs to the technical field of automatic network management and is characterized in that the method comprises the following steps of: automatically discovering all equipments and connection relationship of network to be managed by SNMP polling, memorizing the topology information to a database, dynamically monitoring and collecting the information of the equipment and the link in the network in real time by the SNMP, sending an alarm information when discovering emergent situations, presenting data analysis results in the form of graphs or reports to the network manager by a foreground system, automatically generating the stochastic Petri net mode in the network and arranging input parameters by a background program according to the information in the database, automatically solving the stochastic Petri net model and converting the stochastic Petri net model into network performance indexes by the background program; and simultaneously generating strategy automatically or helping the network manager to generate exacter strategy by the background program. The method automatically discovers, establishes and reflects the topology of the network to be managed, carries out real-time monitoring, information collecting and automatic modeling and analyzing in real-time, and generates the strategy in real-time to adjust the equipment configuration so as to improve the performance of the network to be managed.