The present invention discloses a system and method for phased array sound wave advanced geological exploration for a shield tunneling machine. The system includes a phased array sound wave emitting and receiving apparatus, a probe automatic telescopic apparatus, an automatic protection and cleaning apparatus, and a signal processing and imaging system. Sonic probes are installed on a side wall of a main spoke, opposite to a rotation direction, of a cutterhead of the shield tunneling machine, on the basis of automatic detection of a telescopic state and a contact state, sonic array probes are enabled to make contact with a tunnel face by a hydraulic push rod, a focus sound wave is emitted by using a phased array emitting technology, and a reflected wave signal with front geological information reflected from the front of the tunnel face is received. A scanning direction of a sound wave beam is controlled and changed continuously through a host system, on the premise of obtaining a suspected abnormal body position, the suspected position is imaged in detail by using a focusing image till scanning of a whole two-dimensional section is completed, then the cutterhead is rotated to change an arrangement direction of an array to continue scanning of a next two-dimensional section, and finally three-dimensional geological exploration in front of the tunnel face is realized.