  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 $\eta_\text{N} < 10^{-4}$ 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 $\eta_\text{N}$ 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.
