Disclosed are a method and apparatus for MTC device accessing wireless communication system. The method comprises: after the access network element obtaining the limited factor of the queue length, the normal access rank MTC device obtaining the corresponding limited factor of the queue length by monitoring the broadcasting channel; the MTC device calculating the queue length of its buffer, and judging whether the extending access barring EAB process can be performed according to the calculated queue length of its buffer and the obtained limited factor of the queue length; if not, continuing obtaining the corresponding limited factor of the queue length by monitoring the broadcasting channel; if yes, performing the EAB process, and determining whether random access process to the wireless communication system can be initiated according to the performance result of the EAB process. Applying the invention, the overflow of the buffer can be avoided, which is resulted from that the MTC device with large traffic can not access the network.