Embodiments of this application relate to a signal receiving apparatus and method. The receiving apparatus includes: a signal receiving module, configured to detect a reference pulse signal in a received optical pulse signal where the optical pulse signal is the reference pulse signal and a quantum optical pulse signal; and a synchronization clock module, configured to obtain a modulation pulse signal based on the reference pulse signal. A first intensity modulator in the signal receiving module is configured to obtain, based on the modulation pulse signal, a first local-frequency optical pulse signal having same timing as the optical pulse signal, and the signal receiving module uses the first local-frequency optical pulse signal to interfere with the reference pulse signal and the quantum optical pulse signal separately to obtain a raw key.