The invention provides a top/bottom-level-adjustable pulse baseband generating device for micro discharge effect detection, comprising a linear modulation signal generating circuit, a D/A converter, a linear attenuation control drive circuit, and an electrically-controlled attenuator. The linear modulation signal generating circuit is realized by an FPGA. The linear modulation signal generating circuit includes a narrow pulse signal generating unit and a top and bottom level encoding unit. The narrow pulse signal generating unit, the top and bottom level encoding unit, the D/A converter and the linear attenuation control drive circuit generate pulse baseband signals. According to the top/bottom-level-adjustable pulse baseband generating device of the invention, a top/bottom-level-adjustable pulse signal is conditioned by the linear attenuation control drive circuit and then directly sent to the control end of the electrically-controlled attenuator. The number of steps for pulse modulation signal generation is reduced. A top/bottom-level-adjustable pulse baseband signal is convenient to apply and simple to operate, and the pulse signal can be output by simply setting the top voltage value and the bottom voltage value.