Provided are a signal transmission method and system, and a control information transmission method and apparatus, the signal transmission method includes: a first communication node acquires M sending beams; the first communication node determines N sending beams for sending a first signal from the M sending beams; and the first communication node sends the first signal to a second communication node by using the N sending beams; where M is a natural number, and N is a natural number less than or equal to M.