In my search console number of excluded url is greater than number of valid url. In large number of excluded url will affect the site ranking?
That depends, but yes, most probably.
Any value those pages have towards your website's overall performance will be excluded by Google. Their inherent keywords and content, internal links to and from those pages, and (most importantly) inbound links to your site targeting those pages would all be discounted by Google's ranking of your website.
Conversely, any negative SEO practices (duplicate content, keyword stuffing, etc), would be also discounted. However, any malicious content (malware) contained on these pages would still trigger a warning and possible exclusion of your entire website from the index.
Having lots of pages that Google doesn't want to index won't usually hurt the pages that Google does want to index. It is usually caused by one of the following:
- Your site has lots of pages and little reputation. As your site gains reputation, Google will be willing to index more pages from your site. See Why aren't search engines indexing my content?
- Your site has lots of duplication. When you internally duplicate content between URLs, Google chooses one to index and excludes the duplicates. See What is duplicate content and how can I avoid being penalized for it on my site?
- Your site has low quality pages. If your pages are thin, poorly written, not well received by users, scraped, or spammy; Google will choose not to index them and they could hurt the other pages on your site.