This cave is not only a longest but also the most beautiful cave of Iran given a cave phenomenones. Katale- Khor cave locates at Zanjan province and at 150km Zanjan city. Almost 3/000m from the route of this cave has been performed for building a floor and lighting and prepared for visiting the public. Despite three floors from this cave has been discovered and also from perspective of the longitude the much area of cave has been identified, but there are the undiscovered parts and routes in this cove yet. Kinds of stalagmite and stalactite as simple and composite, fungal-shaped, kinds of lime columns, colloform sediments, strip – shaped relief , lime masses as imaginary pictures, natural volumes similar to animals and other beautiful cave phenomenon s are an observable in this cave. The residence and catering possibilities around cave and it’s access road have a desired quality.