A focusing module for long focal length telescope which includes a sliding plate, a fixing sleeve, and a fixing bolt is disclosed. The drawtube is disposed on the sliding plate for sliding forward or backward to focus. The fixing sleeve and the fixing bolt form a connecting mechanism. When screwing the fixing sleeve to clamp the sliding plate from the bottom, the fixing bolt will be driven to clamp the sliding plate from the top simultaneously. This prevents the main tube and the drawtube from being displaced, and the target can be kept in the field of view of the telescope.