The invention relates to the technical field of electronic detection devices, in particular to a cow oestrus detection necklace which comprises a band-shaped necklace body and an oestrus detection device.The oestrus detection device is arranged on the band-shaped necklace body and comprises an acquirer, a processor and an oestrus warning device, and the acquirer, the processor and the oestrus warning device are sequentially connected with one another; the acquirer is used for acquiring cow activity information and transmitting the cow activity information to the processor via a data wire; the processor is used for judging whether cows are in normal states or oestrus states and transmitting judgment results to the oestrus warning device via a data wire; the oestrus warning device is used for displaying current states of the cows.The cow oestrus detection necklace has the advantages that the cow oestrus detection necklace is simple in structure and is convenient and practical, and the labor intensity can be relieved for observation staffs; activity of the cows is monitored in real time, so that the cow oestrus period disclosure rate can be increased; the optimal mating time can be determined according to disclosed oestrus time, accordingly, the milk yield of the cows can be increased, and the cow oestrus detection necklace is favorable for the economical efficiency.