A reference signal sending method includes the following. A network device sends reference signals of N antenna ports and downlink data to a terminal device, where the reference signals of the N antenna ports include cell common reference signals of N1 antenna ports and reference signals that are of N2 antenna ports and that are specific to the terminal device. After receiving the reference signals of the N antenna ports and the downlink data, the terminal device detects the downlink data based on the reference signals.