The invention relates to a steam generation system for a solar photo-thermal power station and an operation method of the steam generation system. The steam generation system provides a water workingmedium through a water supply unit, and the steam generation system comprises a preheater, a venturi nozzle, an evaporator, a steam pocket and a starting unit. According to the steam generation systemand the operation method of the steam generation system, the feed water kinetic energy is utilized, meanwhile, the venturi nozzle principle is utilized, on one hand, the circulation volume of the steam-water medium between the evaporator and the steam pocket is promoted through the accelerated mixing function of the venturi nozzle, and the structure is between natural circulation and forced circulation; and on the other hand, when the feed water temperature is lower than the molten salt freezing point, the feed water can be mixed with steam water in a steam pocket downcomer through the venturi nozzle, and finally the temperature of the feed water entering the evaporator is increased. According to the steam generation system and the operation method of the steam generation system, the investment of a forced circulation pump is saved, the reliability of system operation is improved, and meanwhile the auxiliary power is saved.