  Under the standard model extension (SME) framework, Lorentz invariance is
tested in five binary pulsars: PSR J0737-3039, PSR B1534+12, PSR J1756-2251,
PSR B1913+16 and PSR B2127+11C. By analyzing the advance of periastron, we
obtain the constraints on a dimensionless combination of SME parameters that is
sensitive to timing observations. The results imply no evidence for the break
of Lorentz invariance at $10^{-10}$ level, one order of magnitude larger than
previous estimation.
