Two parameters for evaluating the performances of 100Gbit/s line transponder are introduced in this paper:receiver Optical Signal Noise Ratio（OSNR）tolerance and pre-FEC OSNR corresponding to the maximum module BER.The former is used to evaluate the overall performance of the hardware and software algorithms of the optical module

while the latter is used to evaluate the performances of the optical module after the software algorithm is closed.Furthermore

the test block is given

tests are performed by using the integral method and the test results are to be calibrated.This test method has certain value of reference for the OSNR tests on other line optical modules.