The invention relates to a position identifying system and a detection method of a multi-layer linear array laser spot. The position identifying system comprises a linear laser transmitter and a detection device, wherein the detection device comprises laser detectors, subsequent circuits, a single-chip machine, a display, an output interface and a power supply. According to the requirements of precision and length, a certain quantity of laser detectors are uniformly arranged and installed at certain intervals to form a linear array as one layer, multiple layers are made in parallel and then are used as one block, and multiple blocks are spliced to form the detection device. The linear laser transmitter forming a required certain position relation with the detection device transmits fan-shaped laser beams, the laser detectors induce the fan-shaped laser beams and generate electric signals which are processed and calculated by the subsequent circuits and the single-chip machine so that the laser detector in the center of the spot can be identified, and the position of the spot in the arrangement direction of the laser detector is obtained. The position information data can be directly displayed on the display and also be outputted by an output interface for other kinds of equipment.