1. how can i run this activiti : https://github.com/Activiti/Activiti from eclipse ? because i didn't found the tutorial for run the activiti from eclipse.
2. if i can run this maven project from eclipse , can i convert the maven project into Java Plugin Project?
I'm not sure what you're looking for… Activiti is a jar. So you can't "run" Activiti from Eclipse. What you can do, is create a Java project (or Maven) and include Activiti and run that.
That is the Activiti source code, and it is a standard Maven project that you can import in Eclipse.
However, for integrating Activiti with another system, you don't need to have the source code. It is enough to depend on the activiti-engine jar (through Maven for example).