An optical component (10), a laser (30), an optical network system (40), and a monitoring method are disclosed. The optical component includes a filter (101), a first detector (102), a second detector (103), an optical beamsplitter (104), and a processor (105). The filter (101) reflects an incident optical signal to the optical beamsplitter (104) and transmits the incident optical signal to the second detector (103); the optical beamsplitter (104) splits a reflected optical signal and make one beam thereof incident to the first detector (102); the first detector (102) monitors the reflected optical signal, to obtain an optical power of the reflected optical signal, and sends the optical power of the reflected optical signal to the processor (105); the second detector (103) is configured to monitor a transmitted optical signal, to obtain an optical power of the transmitted optical signal, and send the optical power of the transmitted optical signal to the processor (105); and the processor (105) adjusts the op
