In electronic and electrical experiments in university laboratories, the oscilloscope is necessary to be used to measure various electrical signals. The universal experimental teaching oscilloscope does not separate the measurement channels, but there may be electrical isolation between multiple measured signals, especially in the experiments of power electronics technology series courses. The reference ground of the measured signal has multiple electrical isolation measurement areas such as control ground, drive ground, and main circuit ground. If a common ground oscilloscope probe is used to measure multiple non common ground signals simultaneously, it can seriously damage the experimental equipment. An isolation sampling device is designed in this paper, in conjunction with oscilloscope, can achieve synchronous sampling of multiple non common ground voltage and current signals. In order to improve measurement accuracy, the isolation sampling device has set up high and low signal measurement channels for voltage sampling and current sampling respectively. However, considering that this device is used in university experiments, there may be situations where the input high voltage and high current signals are connected to the low voltage and low current measurement channels due to operator errors. Therefore, the isolation sampling device is equipped with over range protection circuits and an alarm circuits. The experimental results show that the isolation sampling device can achieve isolation and synchronous sampling of the measured voltage and current signals, and the signal conversion ratio is consistent with expectations.