In order to realize fiber-optic temperature sense based on macrobending loss properties of sinlgle-mode fiber, temperature sensing properties of macro-bend single-mode fiber were studied theoretically and experimentally. Temperature correction is made for a classical macrobending loss theoretical formula of single-mode fiber. Then simulation analysis of effects of bend radius, wavelength and temperature on bend loss of a single-mode fiber with core-infinite cladding structure is made based on the formula. After that, a single-mode fiber temperature sensor with an inner absorption layer and an outer nickel layer outside the cladding layer of the fiber is designed and made. Finally, experimental tests of temperature sensing performance of the sensor are carried out and discussed. Results show that macrobending loss of the fiber with core-infinite cladding structure is sensitive to bend radius, wavelength of light resource and temperature, and the temperature response of the sensor is linear. In addition, the proposed fiber-optic sensor shows a temperature resolution of 0.4 ℃. It′s worth noting that the temperature sensitivity and resolution can be increased by decreasing the bend radius and raising the wavelength of light resource. Thus such single-mode fiber can be treated as core-infinite cladding structure single-mode fiber, which can be used to develop macro-bend optical fiber sensor based on macrobending loss properties.