Ultra-Wideband (UWB) fuze return signals simulator is an effective way for efficient and quick testing of UWB fuzes. The circuit for UWB impulse generation is one key element of the simulator. Current impulse generators are mainly designed for Gaussian pulse or Gaussian doublet, which cannot be used in the simulator directly. Based on sphere target assumption, the current research presented a circuit that can generate second order Gaussian impulse for fuse return signal simulator, using step recovery diode and UWB filter co-design. Parameters of SRD circuit and UWB filter were determined by simulation. According to simulation results, a impulse circuit was fabricated and measured. The measured results coincide with theoretical second order Gaussian signal.