The functional performance assessment of prosthetic components is an important factor in the safe and appropriate prescription of myoelectric prostheses for upper limb amputees. An assessment platform for upper limb myoelectric prosthetic devices is developed for objective evaluation. The proposed platform creates a sequence of activation signals from electromyography data captured from a patient. The signal sequence is used to activate a myoelectric prosthesis for a number of pre-set cycles. The platform then records the actual prosthesis motions and its functional parameters and the results are compared with existing standards or benchmarks. Two commercial myoelectric prosthetic terminal devices are used in an experiment with the platform to verify their gripping performance.