Can we enable alwayson feature of sql 2012 in windows 8.1? I want to enable "AlwaysOn" feature of MS SQL Server 2012 in Windows 8.1

Is it possible to do so?
Short answer is, No.

To enable Sql Server AlwaysOn, the server 


  The server instance must reside on a Windows Server Failover Clustering (WSFC) node. Enable and Disable AlwaysOn Availability Groups, MSDN


Server Clustering is only available on Windows Server OS (i.e. Not 8.1)
Windows Server Clustering

You might want to see Overview of AlwaysOn Availability Groups (SQL Server)

Anticipating further questions, you might want to have a look at other disaster recovery options that you might be able to use: Description of disaster recovery options for Microsoft SQL Server 
Something like log shipping might be the most feasible and easy to set up (assuming you have limited resources, and that's why you have SQL Server installed on Windows 8.1 and not a server)

Edit
Without lingering on this too much, for the sake of completeness I'll point out there is a difference between AlwaysOn Availability groups and SQL Server Failover Cluster Instances, discussed here, the former only available on Enterprise edition. Still both dependant on WSFC though so it doesn't make a difference for you.