The methods of Chan enlightenment and the Chan Kung-an are usually enigmatic, but the Shurangama sutra has plenty and profound indications in the principles of the methods of Chan enlightenment, it can help us to understand the enigmatic methods of Chan enlightenment. Therefore, this article discusses some of the methods of Chan enlightenment and its principles according to the Shurangama sutra. The contents include: 1) the principles of the methods of Chan enlightenment about metaphysics, practice, function and teaching; 2) the processes of Chan enlightenment through "three-cause Buddha nature" and from the existential view; 3) the Chan schools from the principles of Chan enlightenment, and comparing the schools with "the harmony of Chan and Jiao ( teaching traditions )" and "three schools of Chan Buddhism" of Tsung-mi. The Shurangama sutra is extremely praised in Chinese Buddhism. This sutra is specially admired for opening our wisdom. And in Chan Buddhism many persons take this sutra as the standard of practice and view. This article combines discussions of the Shurangama sutra's teaching of opening wisdom, and Chan Buddhism's way of enlightenment. Such can helps us to understand the way of enlightenment of Chan Buddhism. On the other hand, it can also help us to understand the intimate connection of the Shurangama sutra and Chan Buddhism in theory and in method.