Under the standard model extension （SME） framework, Lorentz invariance is tested in five binary pulsars： PSR J0737-3039, PSR B 1534＋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 sen- sitive to timing observations. The results imply no evidence for the break of Lorentz invariance at the 10-l level, one order of magnitude larger than the previous estima- tion.
