The invention discloses a light-weight level power communication network SDN service flow sensing method and light-weight level power communication network SDN service flow sensing system. the light-weight level power communication network SDN service flow sensing method comprises the following steps of performing preliminary detection on a data packet in a service flow; if the condition that no matched table item exists in the service feature of the data packet is detected, packaging and forwarding the service flow to an SDN main controller; performing flow detection recognition on the data packet in the service flow based on a Bayes weighting method and an attribute recognition model to recognize the service feature and service type, and storing the service feature and service type intoa service recognition feature database; according to the service feature and service type, performing computation in combination with a network strategy, network topology and network resources to generate a forwarding flow table of the service flow; and distributing the service flow to corresponding data forwarding equipment according to the forwarding flow table.