I have recently completed my graduation with 62% marks.My age is now 26 years.Now can I appear in Asst Commander exam conducted by UPSC.

Hi, the current UPSC rules state that an individual has to be between “20-25 years” on the date of the Asst. Commandants’ exam.  The rules further state that age relaxation will be given to “certain categories of persons including departmental candidates”.
Thus, unless you’re sure you belong to this special category, I’m afraid you will not be eligible for the exam since you are now 26.