A ∼500 kV/400 kA/100 ns pulsed power generator (PPG-I) for x-pinch experiments was designed and constructed at Tsinghua University. It is composed of a Marx generator, a combined pulse forming line (PFL), a gas-filled V/N field distortion switch, a transfer line, and a copper-sulphate resistive load for testing. The PPG-I implements a novel design in lines that four pieces of waterline with impedance 5Ω in parallel constitute a combined PFL with 1.25Ω, and incorporate each other by a common self-break V/N switch on a matched 1.25Ω transfer line. At the peak charging voltage of the PFL, the V/N switch breaks down in multi-channel discharge mode, and electric energy is fed into the testing load through the 1.25Ω transfer line. This article presents the design and test of the PPG-I generator.