Abstract: The Light Ⅱ-B was built at the side of the Marx tank of Light Ⅱ-A for X-pinch test, which kept the original capacity of KrF excimer laser, and can be used for relevant researches of X-pinch. It is composed of a Marx generator, a pulse forming line (PFL), a gas-filled switch, a pulse transmission line (PTL), and a copper-sulphate resistive load. The medium of the forming line is deionized water. The input impendence of the pulse forming line is 6 Ω, corresponding to an output impendence of 1.25 Ω for the pulse transfer line. The design of circuit simulation and the debugging results in resistance load were introduced. The results show that the current peak load is about 269 kA, pulse width is about 50 ns, and the current rise time is less than 30 ns when the load is 1.25 Ω. It indicates that Light Ⅱ-B has the ability to drive low impedance X-pinch experimental line.