The invention discloses a double-water-tank solar water heater with a porous flow guide separation plate. The double-water-tank solar water heater comprises the flow guide separation plate. The flow guide separation plate comprises a plate and a seal disc which are obtained after the flow guide separation plate is subjected to stamping or extrusion forming. The plate is provided with a flow guide pipe. The seal disc is provided with a breathing hole group, and a breathing hole located in the middle of the breathing hole group is right aligned with the flow guide pipe. The flow guide separation plate has the characteristics that manufacture is convenient and fast, manufacture time of the flow guide separation plate can be shortened through extrusion or stamping forming, production efficiency is improved greatly, installation is convenient and fast, smoothness of water flow between two water tanks can be ensured, and heat exchange of the two water tanks can also be prevented very well.