Provided are a method and apparatus for sending a Device-to-Device Synchronization Signal (D2D SS), and a User Equipment (UE). The method includes: selecting, by a source UE one Zadoff-Chu (ZC) sequence from M predetermined ZC sequences of which a length is N; mapping, by the source UE the selected ZC sequence to a predefined D2D SS source; and sending, by the source UE a D2D SS obtained after the mapping to a target UE. The method effectively reduces mutual interferences between a Demodulation-Reference Signal (DM-RS) and a Sounding Reference Signal (SRS) sent by the target UE and the D2D SS. The apparatus includes: a selection component, a mapping component, and a sending component. The apparatus may also include: a storage component, and a processing component.