How to create a table of related list of object using Nintex Document Generation in Salesforce?

Hello Saurabh

You can achieve this by creating relationship in your docgen packages.

• Go to your Docgen packages.
• Click on to the New Relationship Button
• For Type dropdown :Select salesforce Object
• For Related By (What you have) :Select the object on which you are working.In this case select your parent object.
• Relationship (What you want): Select child object which you want to show on to the table.In this case child object of your parent object.
• Related By: Select relationship between them.
• Click on save button.
• After clicking on save button you will a new relationship created in your docgen package.Click on the edit link of the relationship
• In the Relationship Alias: Give a unique alias which differentiate this relationship with others relationship
• In the Copy type: Select Table
• If you want to show it any order then in the Order Relationship by select field from the dropdown and select Descending if you want to show in Descending order.
• Click on save button
• Now go to the Field Tagger select your child object as Main object after that use  Replicate Table tag from the field tags section in your template.
• On generating document It will generate dynamic table which shows child object related list of parent object

Hope it may helps