The invention discloses an image switching method for automatically judging a water outlet area of a geophysical prospecting instrument and the geophysical prospecting instrument. The method includesthe steps of providing lithology options for a user to select and receiving the lithology selected by the user after a curve graph and/or profile graph are/is generated, and selecting the area of theoptimal water containing layer on the curve graph and/or the profile graph according to the lithology. After the lithology is selected by the user, the curve graph or the profile graph generated by the instrument is automatically analyzed, the water outlet area is automatically indicated, the automatic analysis function of the geophysical prospecting instrument is added, and time and labor cost can be saved for the user.