This　paper　constructed　a　calibration　system　of　oscilloscope　based　on　the　optical　pulse　source.　The　70GHz　sampling　module　86118A　of　Agilent　86100C　was　calibrated　based　on　optical　pulse　source　using　the　standard　pulse　method.　In　the　calibration　process,　the　influences　on　calibration　results　of　three　kinds　of　time　base　errors　were　researched　for　the　first　time,　e.　g.,　time　base　drift　was　removed　using　a　cross-correlation　algorithm,　time　base　distortion　was　corrected　using　the　least　squares　method,　and　jitter　was　removed　by　using　PDF　deconvolution.　Experiment　results　showed　that　calibration　of　70GHz　broadband　oscilloscope　was　realized,　the　time　base　errors　could　be　effectively　removed　by　this　method,　and　the　accuracy　of　the　calibration　was　satisfied.　©　2018,　Chinese　Institute　of　Electronics.　All　right　reserved.