A synchronization information sending method, comprising: determining, by first user equipment, UE, first synchronization information of a vehicle to everything, V2X, system and sending, by the first UE, the first synchronization information to a second UE, the first synchronization information being different from second synchronization information of a device to device, D2D, system, wherein the first synchronization information is different from the second synchronization information in that: - a sequence used for a synchronization signal in the first synchronization information is different from a sequence used for a synchronization signal in the second synchronization information; and - a frequency-domain mapping manner of a sequence used for a synchronization signal in the first synchronization information is different from a frequency-domain mapping manner of a sequence used for a synchronization signal in the second synchronization information, wherein: an even-number subcarrier and an odd-number subcarrier occupied by a second synchronization sequence in the first synchronization information are respectively corresponding to sequences corresponding to an odd-number subcarrier and an even-number subcarrier of a secondary synchronization sequence in a subframe 0 or a subframe 5 in a second link, wherein the second link is a link between the first UE and a base station. determining, by first user equipment, UE, first synchronization information of a vehicle to everything, V2X, system and sending, by the first UE, the first synchronization information to a second UE, the first synchronization information being different from second synchronization information of a device to device, D2D, system, wherein the first synchronization information is different from the second synchronization information in that: - a sequence used for a synchronization signal in the first synchronization information is different from a sequence used for a synchronization signal in the second synchronization information; and - a frequency-domain mapping manner of a sequence used for a synchronization signal in the first synchronization information is different from a frequency-domain mapping manner of a sequence used for a synchronization signal in the second synchronization information, wherein: an even-number subcarrier and an odd-number subcarrier occupied by a second synchronization sequence in the first synchronization information are respectively corresponding to sequences corresponding to an odd-number subcarrier and an even-number subcarrier of a secondary synchronization sequence in a subframe 0 or a subframe 5 in a second link, wherein the second link is a link between the first UE and a base station. - a sequence used for a synchronization signal in the first synchronization information is different from a sequence used for a synchronization signal in the second synchronization information; and - a frequency-domain mapping manner of a sequence used for a synchronization signal in the first synchronization information is different from a frequency-domain mapping manner of a sequence used for a synchronization signal in the second synchronization information, wherein: an even-number subcarrier and an odd-number subcarrier occupied by a second synchronization sequence in the first synchronization information are respectively corresponding to sequences corresponding to an odd-number subcarrier and an even-number subcarrier of a secondary synchronization sequence in a subframe 0 or a subframe 5 in a second link, wherein the second link is a link between the first UE and a base station.