This paper proposed a new index to objectively evaluate the difference of sensory ability between the left and right hand using the amplitude of steady state somatosensory evoked potential (SSSEP). One upper-limb amputee and 13 able-bodied subjects were recruited for this study. Each subject was required to discriminate 3 levels of electrical stimulation frequencies for psychophysical test and the elicited SSSEP was simultaneously recorded. We calculated SSSEP amplitude and discrimination accuracies for each level of stimulation frequency. Then the correlation between the difference of SSSEP amplitude and the difference of discrimination accuracies for the left and right hand stimulation was characterized. The results indicated that there was a positive linear correlation (R2 = 0.7137) between the difference of SSSEP amplitude and the difference of discrimination accuracies for the left and right hand stimulation. SSSEP amplitude feature might be used as a potentially objective index to evaluate the difference of sensory ability between the left and right hand.