The　method　of　separating　singularity　was　applied　to　study　the　uniform　difference　scheme　of　a　singular　perturbation　problem　for　a　semilinear　ordinary　differential　equation　with　mixed　boundary　value　condition.　The　uniform　convergence　on　small　parameter　of　order　one　for　an　Il＇in　type　difference　scheme　constructed　was　proved.　At　the　end,　a　numerical　example　was　given.　The　computing　results　coincide　with　the　theoretical　analysis.