A resident activity recognition method is provided. The method comprises: receiving a plurality of first testing data from a plurality of sensors by a processor, wherein the first testing data includes a present weight set of sensors and present trigger statuses of sensors; determining an activity of a non-target resident at a present time by the processor according to a non-target resident model and the first testing data; reducing a part of the present weight set to generate an updated weight set and a second testing data including the updated weight set and the present trigger statuses by the processor according to the activity of the non-target resident at the present time, the first testing data and the non-target resident model; determining an activity of a target resident at the present time by the processor according to a target resident model and the second testing data.