A kind of focusing structure making use of two worm wheels and two screws was designed, which has tall frequency and tall precision to compensate the shortcomings of traditional focusing structures.According to theory of mechanics of materials, the relation between the amount of supporting and the member’s distortion was analyzed. According to advantage of two supports which tested the direction precision and was tested in a dynamic environment, we had designed and manufactured a new focusing structure. The result of test proves that the frequency in three directions of the focusing mechanism are higher than 220 Hz, and the direction precision is better than 2 after the dynamic environment testing. The focusing mechanism has nice capability to stand against vibration, tall precision, smooth moving, and high dependability, which can make use of fixated and exact removing big dimension focal plane.