Ultra-wide ground penetrating radar has been more and more widely used in the non-destructive testing system, and the sampling circuit is the key to the whole non-destructive system design. A new triode sampling gate is proposed based on equivalent sampling principle. The circuit overcomes the shortcomings of the existing diode sampling gate circuit and can well achieve sample-and-hold. Using Advanced Design System(ADS) software to simulate the sampling gate, 2 ns triangular wave with 10 MHz of pulse repetition frequency is input, and a sampling pulse signal with the sampling clock repetition frequency of 10 MHz and a 100 ps delay difference with the sampled signal is utilized. After the sampling gate, the output signal is 2 μs. This circuit is implemented on FR4, and a 90 ns sine wave is input as a signal to be sampled by using a signal generator. The sampling clock is 100 ns, and the signal period after the sampling gate is 1 μs. The measured and theoretical results show that the circuit can reduce the frequency of the input signal, therefore it can use low-speed A/D to acquire high-speed signal, which greatly cut the cost of the entire system.