A new approach for simultaneous measurement of strain and temperature using a single fiber Bragg grating is proposed and demonstrated. The fiber Bragg grating used for simultaneous measurement of strain and temperature was written on the joint of two different fibers, and has two reflection-peaks at different wavelength. One section of the grating was bonded onto the substrate with large thermal expansion coefficient, so, the two reflection-peaks show different strain and temperature response, and strain and temperature can be measured simultaneously.