Hi Ricardo, it depends on which model you are talking about. It can not have a threaded barrel, pistol grip, or adjustable stock.
Illinois compliant PC Carbine here budsgunshop.com/product_info.php/products_id/56185/ruger+pc+carbine+9mm+10+1+fluted+16+barrel ,
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And here budsgunshop.com/product_info.php/products_id/113037/ruger+-+pc+carbine+9mm+16.12+fluted+barrel+adj+ghost+ring+black+synthetic+10-rd ,
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And here budsgunshop.com/product_info.php/products_id/123861/ruger+pc+carbine+9mm+16.12+flt+usa+flag+synthetic+10 ,
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Stay safe & have a great day!

Hi Ricardo and welcome. Your local FFL should have the latest local gun laws. Just enter your Zip Code and proximity here to find a local FFL dealer : budsgunshop.com/ffl.php

I read the restrictions as yes it is legal however I recommend asking your local FFL as he will be knowledgeable about the latest state and local rules budsgunshop.com/feeds/state_reg/illinois_restrictions.pdf