I want to create report(e.g. PDF,Excel,Word) in ASP.NET Core 1.0, but NPOI and OpenXML is not support ASP.NET Core.
There is an issue for .NET Core support for OpenXML (https://github.com/OfficeDev/Open-XML-SDK/issues/65). Some work has to be done before it is ready. Someone who had your demand as well ported it to .NET Core and published his project on GitHub (https://github.com/xrkolovos/Open-XML-SDK-for-NET-Platform-Standard). I have not tried it myself, but it may be worthwile to try.
UPDATE:
Current releases of OpenXML support .NET Core. Therefore the second GitHub project is obsolete now.