Export Outlook calendar events and then import them into SharePoint calendar

In Outlook

1. Select Calendar
    
2. Choose File > Open & Export, then click Import/Export
   
3. Select options to export to comma separated file
   
4. Then choose a location, give it a name, then click Finish

In Excel

Remove unwanted columns then make a table from the data i.e. Insert | Table | Specify columns and rows to use, click OK

From Design tab, choose Export | Export table to SharePoint list and go through the Wizard

In SharePoint

Create calendar view