A fuzzy random chance-constrained programming based hybrid intelligent algorithm for quantifying the transmission reliability margin（TRM） is presented. The vital factors that influence the reliability of transmission lines are taken into consideration. For instance， the generator and transmission line outage are seen as discrete stochastic variables subjected to the distribution of quadratic forms， and load demand as a random event following the normal distribution. On the basis of randomization for uncertainties， a mathematical model based on fuzzy random chance-constrained programming is developed， whose constraint conditions including the generator， transmission line outage and load demand are introduced as a stochastic function or fuzzy function. Moreover， the hybrid intelligent algorithm for solving this chance-constrained programming model is proposed， and the simulation calculation of the IEEE 30 buses system has been carried out. The advantages， validity and feasibility of the approach proposed are proved by experimental results.