Investigation of the non-ohmic transport behaviors under high magnetic fields can provide a new way to explore novel field-induced phenomena. We present the current–voltage measurements under high magnetic fields based on the flat-top pulsed magnetic field system. Two different measurement strategies were compared, given that the excitation current swept continuously or increased by a series of pulses. For the short duration of the flat-top pulsed field, the continuous current method was adopted and well optimized to reduce the Joule heating and achieve the quasi-static measurements. Finally, the non-ohmic behaviors of a quasi-one-dimensional charge density wave Li0.9Mo6O17 were successfully studied under the magnetic field up to 30 T at 4.2 K, which was the first current–voltage measurements carried out in pulsed magnetic fields.