A urea solution quality determining system may include a urea tank in which a urea solution is filled through a charging hole, a test chamber positioned below the charging hole for holding a portion of the urea solution, a main line connected to the urea tank at a lower part of the urea tank below the test chamber, a test line connected to the test chamber, a pumping line to which the main line and the test line are joined, a pump in the pumping line to pump the urea solution from the test chamber or from the urea tank, a control valve for selectively connecting the main line or the test line to the pumping line, and an injector at an end of the pumping line to inject the urea solution into an exhaust line through which an exhaust gas flows. A method is also described.