Evaluate what type of book you have to present to a publisher. You should know the target age range and the genre of the book. Some children's book publishers do not publish picture books. Others may specialize in history and educational books. Make a list of all the genres and categories your book falls under so that you can target which publishers may be interested.
Research children's book publishers to find one that may want your book. Look at books similar to yours and see who the publishers were. Go through publisher's websites to see what type of books they have recently published. Purchase a current copy of the "Children's Writers' and Illustrators' Market" or "Children's Writer Guide," which are two trade publications that list children's book publishers and specifics about them.
Join a writing group to network with other authors. They can give you tips and possibly introduce you to their publishers and agents.
Hire a literary agent if you are still having trouble getting a publisher's attention or finding one that suits your needs. Agents will evaluate your manuscript and help you contact the most suitable publisher for your book.