The invention discloses a testing method for response time of an FBG temperature sensor. The testing method is based on a response time testing device. The method mainly includes a reference FBG is fixed on an optical fiber clamp in a non-stretched manner and the central wavelength is kept as 1525 nm; the central wavelength of the reference FBG is adjusted to be identical with the wavelength of ato-be-tested FBG; a broadband light source is switched on; the reference FBG is put into a heating box and a required temperature value of 50 to 100 DEG C is set, and the to-be-tested FBG is put intothe heating box after the temperature is stabilized for 30 minutes; a data collection card sends signals from a photoelectric detector into a computer for analysis and normalization is performed on the signals collected by the collection card; the response time of the to-be-tested FBG is evaluated with a time constant Tau and is defined to be time consumed by that the temperature rises to 63.2% ofa steady state value. According to the invention, the response time is obtained through convolution operation of reflectance spectrum of the to-be-tested FBG and the reference FBG, influence caused by a demodulator on response time testing is avoided and the detection precision is high.