Hi @kong
1.Select Approval - SharePoint 2010, right click and choose copy and modify.

2.Click “Approval Workflow Task(en-US) Copy” to access task process page:

3.Then we could click “New” to add a new task form field, choose the “Person or Group” information type, and enter the name you want to display:

4.Click next to configure the settings, finish it and publish the workflow.

Then go back to the workflow settings page, click the task form in infopath:

Now you could see a new people picker control in the form.

If an Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.