Abstract: A fiber temperature and pressure sensing system for undergraduate teaching is designed，a diode laser with 650 nm is used as light source，and the output is divided into two beams by a beam splitter，which are then coupled into two fibers by a lens，one of the fiber is wound around a PZT tube，and the other fiber by making the shape of a torus is put in a temperature controlled box，the ends of the two fibers are closely coupled to form a double fiber interference system. By measuring the movement of the interference ring caused by pressure and temperature changes，the relation between the change of the temperature and pressure and the fringe number is established. The experimental system has advantages of simple structure，low cost and easy operation and so on，the system can be set up by the students themselves，and it can effectively improve students' experimental ability and mastery of theoretical knowledge，and it is suitable for experimental teaching of optical fiber temperature sensing and optical fiber pressure sensing in photoelectric information science and engineering specialty and similar specialty in universities.

Key words: sensor, double optical fiber, temperature, pressure, experiment teaching