Hi, Can any one tell me,what is the difference between data type changing option in External Column and Output column in Advanced editor of OLEDB Source? If i want to change datatype of one of my column,whether i need to change both? Same thing is there in OLEDB Destination as well.But there input column datatype is not active.Can ny one explain?

Check this thread which explains the difference between external columns and output columns. As such if you want to change the data type/ length you do it on the output columns. However you might get runtime issue when SSIS tries to cast the data into the data type specified. Better use a data conversion transformation. http://btsbee.wordpress.com/