The invention specifically provides a method for measuring the attitude of an optical fiber inertial navigation system in response to the abrupt change of ambient temperature to overcome the problem of the abrupt change of drift of a fiber-optic gyroscope due to influence of ambient temperature. According to the method in the invention, the initial latitude of a carrier is determined by using a global positioning system (GPS); then coarse alignment is carried out on the optical fiber inertial navigation system by using an analytical coarse alignment method under the condition of a static pedestal according to the output information of the fiber-optic gyroscope and an accelerometer, and a preliminary strapdown matrix T is determined, so the process of coarse alignment is completed; and a fiber-optic ring mounted on the fiber-optic gyroscope is provided with a temperature detecting device which can sample ambient temperature in the process of fine alignment and sampling frequency is once each second, so the gradient of ambient temperature can be monitored in real time. The method employs the temperature detecting device to measure the temperature changing gradient of an alignment environment of the optical fiber inertial navigation system, allows the process of fine alignment on the basis of initial alignment to be switched between two manners, guarantees that a system rapidly and accurately completes aligning tasks and eventually improves the measurement precision of an initial attitude angle.