Hi Ajay,
Are you referreing to workflow Template ID ? You can find that in the URL.
In the Ribbon, Library Tools, Documents tab, click “Workflows”
In the “Start a New Workflow” section, right-click on the url that has the name of your workflow and select “Copy Shortcut”
Look at the Url and extract the Guid from the TemplateId parameter. For example, in this url:
http://mysharepointsite/_layouts/IniWrkflIP.aspx?List={21303f3e-d36c-40f2-806e-0d2536b4ec72}&ID=4&TemplateID={aed94889-39bc-4eb9-997b-302d0f55c645}&Source=http://mysharepointsite /