In lib/inc/php-export-data.class.php we have a code:

if(preg_match("/^-?d+(?:[.,]d+)?$/",$item) && (strlen($item) < 10)) {
$type = 'Number';
}

If length is < 10 and is number, then we'll export number format in excel export.
You can change this logic for your case.

thank you sir,

but that is not a number field.that is the varchar field but it will contain only the numbers like account details such TIN NO,ACCOUNT NO like that

how to solve this?

You can comment out above code and all fields will export as text.
Second option is to use custom excel export and put conditions to writeLabel or writeNumber for formatting.
Refer xlsWriteLabel function in demos > export > custom export code.

Thank you sir,

i have used the custom export and it is working well thank you