In order to meet the miniaturization, portability and wide-angle needs for modern medical endoscopes, an ultra-small medical endoscope lens with a wide angle is designed combining with modern plastic aspherical and injection molding technology and using Zemax optical design software. The lens uses two plastic aspheric lens, whose optical structure is in the form of a negative-positive construction and are located by the sides of the stop. The design result shows that F number is 6.0,the field of view is 150° , the total length of the lens is 3.38 m and the lens diameter is 2 mm. The modulation transfer function (MTF) of all fields at half of Nyquist frequency are more than 0.45. Through the test of the lens, the image is clear and the detail of human internal organization can be well observed, which meets the requirement of medical application.