There is a problem of poor timing accuracy on a PTP network caused by the asymmetry of SDH communication delay in a power system. Adopting the characteristics of an SDH network and the IEC-61588 standard, this paper introduces a method to choose the appropriate PTP time synchronization mode for the SDH network, and presents a new PTP path delay compensation strategy for asymmetric paths. Using this strategy gives the application scheme with the PTP clock devices. After a three-day test, the time synchronization accuracy is within 1us. As is shown in the test results, the PTP timing accuracy on PTP network is much improved, and meets the time synchronization requirements for an intelligent substation. This work is supported by the National Social Sciences Foundation of China “Research on Bi-punishment Quantile Regression Modeling Method for High-dimensional Complex Panel Data” (No. 17BJY210).