Objective This study was to study the effect of monovision contact lens (MV-CL) on distant and near vision,distant and near stereopsis,and to identify the effect of degree of monovision on vision function.Methods A prospective case observational study was designed.The clinical data of sixty-eight eyes of 47 cases were collected from November 2010 to August 2014 in Henan Provincial Corps Hospital,Chinese People's Armed Police Forces.Sixty-eight eyes of 47 cases wore contact lenses to improve near vision,in which the other eye of 21 cases with hyperopia wearing contact lenses to improve distant vision.Besides,far and near stereopsis were measured before and two weeks after wearing lenses respectively;and scotopia were measrued with lenses and in naked eyes respectively.Compared the changes of vision and stereopsis in patients before and after the MV-CL,and conducted the patient satisfaction survey.Results There were 89％ (42/47 cases) and 6％ (3/47 cases) of the patients whose naked far and near vision was 0.8/0.33 (J4) at 2 weeks after MV-CL and before MV-CL,respectively.There were no statistical significance about change of near stereopsis with Titmus stereopicture and the Yan's near random-dot stereogram (x2=1.30,0.56;both at P＞0.05).There were no statistical significance about change with apparent machine random dot stereogram iterative crossed parallax and uncrossed disparity (x2 =0.16,0.11;both at P＞0.05).The far distance fusion range and far stereopsis were not significantly different between before and after MV-CL (x2 =0.22,0.16;both at P＞0.05).Titmus stereopicture tests showed that there was a decrease in the number of people who had foveal stereopsis,while an increase was found in people who had macular stereopsis after MV-CL,but the difference had no statistical significance (x2 =2.28,P ＞ 0.05).Conclusions Near vision can be obviously increased and presbytism can be relieved by MV-CL.Stereopsis of some patients are decreased after MV-CL,but this can be accepted by the patients and there is no obvious decrease in far range of fusion.