The invention discloses an engineering geological exploration system. The engineering geological exploration system comprises a hole diameter adjusting mechanism and is characterized in that an adjusting motor is fixedly connected to the inner wall of the hole diameter adjusting mechanism, a threaded rod is installed at the output end of the adjusting motor, a threaded sliding block is in threaded connection to the outer wall of the threaded rod, supporting rods are rotationally connected to the outer wall of the threaded sliding block, and the end, away from the threaded sliding block, of the supporting rods is rotationally connected with a connecting plate. According to the engineering geological exploration system, through the arrangement of the connecting plate, in the hole diameter adjusting mechanism, the adjusting motor works to drive the threaded rod to rotate, the threaded rod rotates to drive the threaded sliding block to move, the threaded sliding block drives the connecting plate to rotate through the supporting rods, the number of the supporting rods is three, the connecting plate moves to drive an energy absorption spring to move, force borne by a rotating blade is transferred through the energy absorption spring, the service life of the rotating blade is prolonged, the connecting plate rotates to drive the rotating blade to adjust the angle, the rotating angle of the connecting plate is 30 degrees, and the hole diameter of a drilled hole is adjusted.