D2D transmission method and device

The invention provides a D2D (Device to Device) transmission method and device. The method includes that a device searches a first synchronization signal and determines whether to send a second synchronization signal or not according to the searching result; the device determines resource used for D2D transmission on the basis of searching the first synchronization signal; a D2D signal and/or D2D data are transmitted on the resource. According to the invention, D2D detection problems in external scene where semi-covering and full-covering cannot be realized in related art are solved and D2D detection effect among devices is achieved further.