Measurements of the total reaction cross section for proton drip line nucleus 12N at about 50.4 MeV/u on Si target were performed on RIBLL. Compared with its neighbor 13N, large enhancement of total reaction cross section σr for 12N is observed. This might be caused by nuclear deformation and nucleon pair effect, and the experimental inaccuracy should not be neglected. The σr of 12N calculated by using a microscopic Glauber model is in agreement with the experimental results.