A fan noise-lowering structure includes a fan frame main body and a connection section. The fan frame main body has a bottom side and a frame peripheral wall. The frame peripheral wall is perpendicularly annularly disposed on the outer rim of the bottom side. The inner rim of the frame peripheral wall defines an airflow passage. Two ends of the airflow passage respectively have an inlet and an outlet. The connection section is disposed in the frame peripheral wall. Two ends of the connection section are connected with the frame peripheral wall. The two ends of the middle passage are an inlet end and an outlet end in communication with the airflow passage. The connection section serves to guide the high-pressure air of the outlet to jet toward the inlet so as to achieve multiple noise-lowering effects.