Jianwei
Best option for you would be to use a Current Probe, for example a Tektronix P6042 or similar.
However there are a number of 'DIY' AC Current Probe designs based upon Ferrite Torroids if you have the facility to calibrate them.
Some info for how you might make one here:Simple RF Current Probes
Another alternative could be to try using a series resistance and view the voltage across it with a Differential 'Scope input to then be able to calculate your pulse current.
an opamp based transimpedance amplifier with low bias current shall be used.......adjust the feedback and derive the current from the output voltage......