It needs to be critiqued by a professional writer, editor, or artist. Take a class at a local college. Join a writer's or illustrator's group, preferably one where real criticism is offered. One thing that you can do to develop your sense of what might interest publishers is to read many current children's books, and learn what is out there. Don't do this so that you can imitate current successful writers or illustrators, but so that you will know if your work is a good match for the publishers you may end up contacting.
Publishers open, close down, and move constantly.
Half of them don't look at unsolicited material. Then try to find the right publisher. This is the nearest thing to a complete source, as it lists publishers of every size, agents, even packagers. It not only describes publishers' programs, but notes whether a publisher is accepting unsolicited mss. They also help organize local writer's groups, folks who get together to read and critique one anothers' manuscripts.