The invention discloses a system for saline-alkali soil improved paddy planted rice. The system comprises a base layer, a straw layer laid on the base layer and a paddy field tillage layer located above the straw layer; a closed conduit communicated with the straw layer is arranged inside the base layer in a spaced mode, and a culvert pipe extending into the closed conduit is arranged in the strawlayer; a plastic soft with open holes over the body is laid in the closed conduit, and a water outlet of the plastic hose extends out of the rice field. The rice stalk is used for supporting and combining the closed conduit for constantly draining out underground water, an air layer is formed under the paddy field tillage layer, and by means of the siphon empty break principle, upward conveying containing salt water is stopped; rice stalk is adopted as the biological culvert pipe, salty underground water backed to the stalk layer is guided into the closed conduit.