how-to-set-a-minimum-word-count-for-wordpress-posts

function minWord($content)
{
	global $post;
	$content = $post->post_content;
	if (str_word_count($content) < 100 ) //set this to the minimum number of words
	wp_die( __('Error: your post is below the minimum word count. It needs to be longer than 100 words.') );
}
add_action('publish_post', 'minWord');