A current-model Triple Langmuir probe was developed and used to measure electron temperature and density of the Pulsed Plasma Thruster plume. To decreasing the errors in measurement, Probe, collection circuit and glow cleaning devices were elaborately designed. A FIR digital Filter based on Matlab was designed and the software for date processing was developed by Labview. Measurements were taken at various position in the plume of a Pulsed Plasma Thruster operating at discharge energy of 6-24J. The results show the thruster plume has electron temperatures in the range between 0.6and 5.4eV, electron densities between 0.9×1019 and 4.1x1021m-3 for all discharge energy levels considered. Electron temperature and density decrease with increasing angle away from the centerline and with decreasing discharge energy.