You could consider submitting a long youth novel to different publishing houses, depending on the type, theme, plot, and style of the novel. Some common publishing houses include: 1. Children's Literature Press: Fictions suitable for children can usually be found here. 2. Youth Literature Press: This type of novel usually focuses on young people, including love, friendship, growth and other elements. 3. Literature and Art Press: The publishing direction of the Literature and Art Press is relatively broad, covering all types of novels, including youth novels. 4. The novel publishing house mainly published various types of novels, including youth novels, suspense novels, science fiction novels, etc. 5. Popular Culture Press: The publishing direction of the Popular Culture Press is mainly for the general public, including various types of novels, but it may not be as targeted as other publishing houses for specific reader groups. When choosing a publishing house, one could first determine the type and theme of the novel, and then understand the publishing direction and style of each publishing house in order to better choose a suitable publishing house for submission. At the same time, he could also try to submit more manuscripts to see which publishing houses could receive the manuscripts and give better publishing suggestions.