Before you submit your children's book to a publisher it is wise to carry out a thorough research. Visit the book stores and libraries to find out which publishers publish children's book of the type that you have written. This research would help you list a few publishers that you could approach. Then find out if they accept full manuscripts or query letters. You would have to keep the latter one drafted in advance. Most of all, do not expect a prompt reply. It is a time taking process that requires you to keep your calm before you get to hear an approval from the publisher.