A power transmission system for a hybrid electric vehicle may include an engine, a planetary gear set, and first and second motor/generators, and transmit rotational power of the engine and rotational power of the second motor/generator to a final reduction gear including a differential through independent paths, respectively, in which a sun gear is directly connected with the first motor/generator through a first motor shaft and selectively connectable with a transmission housing, a planet carrier is directly connected with an input shaft and connected with the transmission housing with a one-way clutch and a torque limiter positioned therebetween, a ring gear is directly connected with a first output gear and connected with a final reduction gear through a first intermediate shaft, and the second motor/generator is directly connected with a second output gear through a second motor shaft and connected with the final reduction gear through a second intermediate shaft.