1. Go to Dataloader Pro.

2. Click Create Job.

3. Select Source and Destination orgs.

4. Click Login and Fetch objects button.

5. Select the Master object. In this case, select parent object. I have selected Account object.

6. Select the related objects. I have selected Contact.

7. Click Save button.

8. Select Filters if needed.

9. Add the filters and LIMIT(optional).

10. Click Run button to run the job.