Highly accurate binary-pulsar timing plays an important role in test of General Relativity. In this Letter, we argue that PSR J0337+1715, a milli-second pulsar in a stellar triple system, could be a very good laboratory for testing the strong equivalence principle (SEP). From the reported orbital parameters of this triple system, we give an uplimited estimation of the Nordtvedt parameter $��_\text{N} < 10^{-4}$ based on the orbital polarization calculation. This result is slightly better than the existed ones. In addition, if based on the observed uncertain value of inner orbital eccentricity, we even can obtain $��_\text{N}$ up to $10^{-7}$, which needs to be confirmed in future. However, more rigorous and accurate measurement of the Nordtvedt effect should be taken from more timing data of PSR J0337+1715.