The following solution helped me:
Created a new environment variable in Windows:
After restarting Eclipse and Quartus it worked.
Thank you for your reply.
although i resoved this issue, i don't know why, for example, what's the usage of this environment variable? and from the forum, i found many guys met the same issue as me but with different solutions.
why intel doesn't put all this solution into a document which works as a detailed guideline for EDS installation so that the new comer can run smoothly instead of wasting time.
it took me 5 days to install the nios ii EDS successfully.
thank you again.
So that locations specified in that particular system environment variables will be used for software packages and driver searching. Will reflect your suggestions to internal for further improvement. Thanks for your reminding.