The feature of developed digital fiber-optic differential protection(DFODP) based on IEC 61850-9-2 standard is analyzed. The particularity of DFODP based on IEC 61850-9-2 standard, building of test environment, essential test points and problems needed to be considered during test are summed up. Some bugs in products of DFODP are found through the practical tests, and their solutions are put forward.