On basis of the nonlocality without entanglement proposed by Bennett,the properties of an orthogonal set of product states of two qutrits are revealed,i.e.,the transformation among different composite spaces can be realized by using three unitary operations,and the correlation between two composite spaces is found. These properties can be used to quantum communication and quantum cryptography. As examples,we propose a scheme of controlled quantum secure direct communication and one of quantum key distribution. It is shown that applying the product state of qutrit to quantum information processing not only is of the advantages of large capacity and high efficiency,but ensures the security.