Abstract: The generalized beam propagation factor(MG2 factor) of circularly symmetric truncated Laguerre-Gaussian beams is studied using the generalized truncated second-order moments method. A closed-form expression for the MG2 factor is derived and illustrated with numerical example. It is found that the MG2 factor of circularly symmetric truncated Laguerre-Gaussian beams depends on the truncation parameter and beam order,and asymptotically approaches the value of circularly symmetric untruncated Laguerre-Gaissain beams as the truncated parameter increases.