The present invention provides an obstacle detecting system and method. The obstacle detecting system includes: a transmitting unit which emits a laser signal; a MEMS scanning mirror which scans detecting regions set at an angle of view at which obstacles in front of a vehicle are detected and a cut-in situation when a vehicle in a next lane suddenly cuts in is detected, and divides the detecting regions into a plurality of regions to scan the plurality of regions at different point intervals; a receiving unit which receives the laser signal transmitted from the MEMS scanning mirror to detect information on an object detected in the detecting regions; and a processing unit which detects the obstacles and the cut-in situation through the information detected in the receiving unit to issue an alarm or transmit a braking command.