The present invention provides a network access method and system for Machine Type Communications (MTC), wherein the method comprises the following steps: an MTC device sends a preamble to a base station; the base station sends a Random Access Response (RAR) to the MTC device; if the RAR does not contain a temporary access resource assignment indication, the MTC device sends a Layer 2/Layer 3 message to the base station; otherwise, the MTC device re-attempts to perform network access; the base station sends a contention resolution message to the MTC device; if the contention resolution message contains a self-identification contained in the Layer 2/Layer 3 message sent by the MTC device, the network access is completed; if the contention resolution message contains the temporary access resource assignment indication, the MTC device re-attempts to perform the network access; otherwise, the MTC device attempts to perform the network access using the originally used access resource again. According to the present invention, it is enabled to dynamically and quickly perform assignment and release of MTC access resources based on actual access resource collisions, which thereby avoids waste of uplink resources in a semi-static configuration, reduces the possibility of collision, and protects normal access of non-MTC devices.