The invention discloses a net cage positioning and clamping device and a positioning and clamping method. The net cage positioning and clamping device comprises two pneumatic latches which are oppositely arranged on the inner side surfaces of two rotating arms of an electric rotating fork truck, two rectangular iron plates which are arranged on two side surfaces of a net cage in a concentric manner, a first electromagnetic proximity switch and a second electromagnetic proximity switch which are arranged the inner side surface of one rotating arm. Each rectangular iron plate is provided with a central hole corresponding to one pneumatic latch, when the pneumatic latches are inserted into the central holes, the circumference surface of the first electromagnetic proximity switch is contacted with the lower bottom surface of the rectangular iron plate corresponding to the first electromagnetic proximity switch, and the circumference surface of the second electromagnetic proximity switch is contacted with the inner side surface of the rectangular iron plate corresponding to the second electromagnetic proximity switch. The net cage positioning and clamping device is characterized in that the electric rotating fork truck only needs to position the two rectangular iron plates which are arranged at two sides of the low-precision net cage in the concentric manner, the low-precision net cage does not need to be excessively reconstructed, the reconstruction cost of the net cage is greatly reduced, only the single side iron plate of the net cage serves as an induction standard, the positioning precision is improved, and the positioning method is simple.