How To Assign Permission Set For Multiple Users Through Salesforce Data Loader?

Hi Manpreet

Below are the steps:-

>> Make sure you have 2 columns in the file (User id & Permission set id)
>> Open the Dataloader–Check the checkbox “Show all objects)–Select the Object as “Permission set assignment”
>> Columns in the Dataloader mapping:- User id=Assignee id & Permission set id=Permission set id

Note:- Select the Insert action.

For more info:http://www.infallibletechie.com/2013/05/how-to-assign-permission-set-for.html

Hope it may help you: