Differential phase shift quantum key distribution(DPSQKD) experiment based on weak coherent pulses have been performed in the laboratory. We encoded the bit information between the consecutive pulses. The bit information was decoded at Bob's side by Michelson-Faraday interferometer and single photon detector. This kind of quantum key distribution system can provide stable key distribution process, high efficiency of key creation, and high security key. So it is easily implemented in optical fibers using readily available optical telecommunication tools. We experimented DPSQKD over 76 km on fiber, the error rate of the sifted key is 5.3%. The quantum key distribution process is controlled by micro-computer based on ARM (advanced RISC(reduced instruction set computing) machines) processor.