A digital content rights management method controlled by time, which is characterized in comprising: a registration step, in which a device for accessing the digital content registers in a digital content rights management system and generates a system register code and a random key, and the system register code is encrypted by using the random key; a time stamp generating step, in which the device for accessing the digital content generates a time stamp as a guide for verifying the time; a time stamp verification step, when the device for accessing the digital content starts up, the validity of the time stamp is verified, if the verification passes, the next step is performed, and if the verification fails, the access of the digital content is not allowed; a step of acquiring a certificate of authorization, in which the device for accessing the digital content acquires a certificate of authorization for accessing the digital content from a server, and the certificate of authorization specifies a starting time and an ending time of allowing to access the digital content; a time verification step, when the device for accessing the digital content accesses the digital content, the time stamp is verified with the time in the certificate of authorization to determine whether or not the device for accessing the digital content is allowed to access the digital content, wherein in the time stamp generating step, the time stamp is written in a memory of the device for accessing the digital content, the random key is positioned in the time stamp, and the time stamp further includes a version number of the device for accessing the digital content, a starting time of the device for accessing the digital content, a verification code, and the latest time for acquiring the certificate of authorization, and wherein in the time verification step, the device for accessing the digital content verifies the time when accessing the digital content, firstly, the starting time in the time stamp is acquired, and if the current system time is earlier than the starting time, it is determined that the system time has been modified; then, the device for accessing the digital content acquires the latest time for acquiring the certificate of authorization in the time stamp, and if the current system time is earlier than the latest time for acquiring the certificate of authorization, it is determined that the system time has been modified; finally, the device for accessing the digital content randomly extracts starting time fields from a number of certificates of authorization, and if the latest time for acquiring the certificate of authorization in the time stamp is earlier than any starting time, it represents an error of the time stamp. a registration step, in which a device for accessing the digital content registers in a digital content rights management system and generates a system register code and a random key, and the system register code is encrypted by using the random key; a time stamp generating step, in which the device for accessing the digital content generates a time stamp as a guide for verifying the time; a time stamp verification step, when the device for accessing the digital content starts up, the validity of the time stamp is verified, if the verification passes, the next step is performed, and if the verification fails, the access of the digital content is not allowed; a step of acquiring a certificate of authorization, in which the device for accessing the digital content acquires a certificate of authorization for accessing the digital content from a server, and the certificate of authorization specifies a starting time and an ending time of allowing to access the digital content; a time verification step, when the device for accessing the digital content accesses the digital content, the time stamp is verified with the time in the certificate of authorization to determine whether or not the device for accessing the digital content is allowed to access the digital content, wherein in the time stamp generating step, the time stamp is written in a memory of the device for accessing the digital content, the random key is positioned in the time stamp, and the time stamp further includes a version number of the device for accessing the digital content, a starting time of the device for accessing the digital content, a verification code, and the latest time for acquiring the certificate of authorization, and wherein in the time verification step, the device for accessing the digital content verifies the time when accessing the digital content, firstly, the starting time in the time stamp is acquired, and if the current system time is earlier than the starting time, it is determined that the system time has been modified; then, the device for accessing the digital content acquires the latest time for acquiring the certificate of authorization in the time stamp, and if the current system time is earlier than the latest time for acquiring the certificate of authorization, it is determined that the system time has been modified; finally, the device for accessing the digital content randomly extracts starting time fields from a number of certificates of authorization, and if the latest time for acquiring the certificate of authorization in the time stamp is earlier than any starting time, it represents an error of the time stamp.