The present disclosure provides an insulation detection circuit, a detection method and a battery management system. The insulation detection circuit includes an isolated power module, first positive and negative sampling modules, second positive and negative sampling modules, and a processor. A first end of the second positive sampling module is connected to a positive electrode of the isolated power module and a second end of the positive switch module, a second end of the second positive sampling module is connected to a second reference voltage terminal; a first end of the second negative sampling module is connected to the second reference voltage terminal, a second end of the second negative sampling module is respectively connected to a negative electrode of the isolated power module and a second end of the negative switch module; and the processor is connected to sampling points.