The invention relates to the field of sensing technology application, in particular to a sensing device for monitoring animal physiological behavior signals in real time and a method for carrying out judgment and classification on animal oestrus and physical conditions. The sensing device comprises a flexible sensing assembly worn on the body of an animal, a wireless network transmitting system and an upper computer on a monitoring center. The flexible sensing assembly comprises minitype sensing function modules for measuring the exercise amount, the temperature, the blood pressure and the electrocardio of the animal, all signals collected by the sensing function modules are transformed, processed and then sent into a minitype storage, and then the signals are uploaded to the upper computer of the monitoring center through the wireless network transmitting system. The minitype sensing function modules, a minitype power supply module, a microcontroller, the minitype storage and a minitype wireless sensor are all arranged on a strap-shaped flexible substrate and are covered by a thin film layer. The whole system is small in size, soft, flexible, convenient to use, suitable for carrying out long-term real-time monitoring on daily activities and physical conditions of animals, capable of accurately judging oestrus behaviors and physiological conditions and is beneficial to supervision of the whole production and circulation process of livestock.