Hi Sunil,
There are 2 webservices available for PerformancePoint Services.
PPSAuthoringService : used by Dashboard Designer to create, modify, and delete dashboard objects, retrieve dashboard content, and retrieve data from data sources.
PPSRenderingService : used by Dashboard Designer and the browser to render dashboard objects
Please note that it is not supported to call these services remotely.
More details : http://msdn.microsoft.com/en-us/library/office/ee554986(v=office.14).aspx
Hope that helps.
Cheers
Rgis