By means of static loading and destruction test on two 18 m span bird-shape plates before and after strengthening, the change of the bird-shape's bearing capacity is analyzed which is strengthened by external tendon. It is indicated by comparing the theoretic results with those of tests that the bird-shape's bearing capacity is raised to some extent after strengthening, the plate's stability confined the increment of bearing capacity, and reinforcement by the curved line-shape tendon is superior to that by the straight line-shape tendon.