Xiao Ming read a book with 600 pages and planned to finish it in 10 days, so his daily reading plan was 600/10 = 60 pages. In fact, he read 30 pages less than he planned, so the number of pages that Xiaoming actually needed to read every day was 60 - 30 = 30 pages. Therefore, the number of days Xiaoming actually needed to read was 60 pages/30 pages/day = 2 days. Therefore, Little Ming actually needed two days to finish reading this book.