can we convert exel file to XML file using informatica ?

There is no default driver available for reading from Excel files. You need to export the Excel file into a comma delimited or tab delimited file and then you should define a XML type Target and load it.

first we need to save the excel file in csv file and then we have xml transformation in informatica by using that we can convert csv file to xml file

Excel source is possible through File DSN - Target XML also can be done - read the documentation or help for more information