For requirement of quantity transmission in broadband measurement system, a unipolar rectangular pulse source is designed to realize 10 kV rectangular wave pulse output with MOSFET as the core component based on Marx circuit. The modular and miniaturization of the pulse generator is realized by using the stack structure to build the 12-stage prototype. The experimental results show that when the input voltage is 850 V, the proposed pulse source can generate a fast output pulse with 10 kV maximum voltage, rise time less than 100 ns, 200 μs pulse width under the capacitive load below 300 pF. The power supply can be used in rectangular wave response performance test of broadband measuring equipment or pulse power related applications.