The invention relates to a flow-control and variable-temperature spray drying system which comprises a heating device, a spray drying tower and an induced draft fan, wherein the spray drying tower comprises an uniform-air section, a tower upper cone, a barrel and a lower cone body from top to bottom; the side wall of the uniform-air section is connected with a tower body hot-blast main pipe; the side wall of the tower upper cone is connected with a feed liquid pipe; the inner end of the feed liquid pipe is connected with a feed liquid atomizing device; the feed liquid atomizing device is positioned on the axis of the barrel; the lower end of the barrel is connected with a tower body exhaust pipe; a finished product discharge valve is mounted at a lower port of the lower cone body; an air outlet of the heating device is connected with the tower body hot-blast main pipe; at least one barrel rectifying ring capable of forming an annular downward air flow on the inner wall of the barrel ismounted on the circumference of the barrel of the spray drying tower; the barrel rectifying ring is coaxial with the barrel; the outer side wall of the barrel rectifying ring is connected with a barrel rectifying ring blast pipe; a plurality of temperature gradients are formed in the tower body from top to bottom. The spray drying system can avoid wall sticking and realize online variable-temperature control, and the product has the advantages of high yield and good quality.